Alright. This one was a doozy. The short and simple answer is that yes, almost all modern scholars agree that there was a "Bronze Age Collapse," even if they debate its extent, severity, and causes. Rather than explaining the details of that, I'll just point you to the many excellent answers by u/Bentresh and this AMA with Eric Cline (a specialist of the Bronze Age Collapse). For your own research, I recommend Bentresh's thread on reading recommendations through that link. Regarding the Sea Peoples, they certainly existed, or at least a group of different peoples identified by that name under Pharaohs Rameses II, III, and Merneptah. We just have that in ancient writing (pdf). In addition to the relevant answers from Bentresh linked above, I'll also recommend this one from u/kookingpot. Regarding Bronze vs. Iron, they're actually correct over on the other site, even if it seems to be a bit of a meme for them. u/wotan_weevil provides an explanation of why/how bronze was actually a more reliable material than early iron in this post.

Now, on to the real reason I spent an hour reading 30 year old book reviews this morning. Wanting to research an answer for yourself is absolutely admirable, and I recommend following any links to sources you find in the posts linked above. You can also use tools like jstor.org and Google Scholar to find quality, academic research or your local university library. Most have website you can access without a log-in and find titles to search for elsewhere. However, very few of the sources you find that way are going to help explain why there are a few users over on Historum pushing this "it never happened" narrative. It's simply so far outside the mainstream that it doesn't even merit debunking in most papers focused on the Collapse itself.

I'd never heard of the site before and decided to check it out, thinking it was probably just a matter of poor explanation that the Bronze Age Collapse was really more of a 200 year process of old systems slowly falling apart. I did see some users trying to explain that, but I also found a couple of seeming power users on Historum who heavily pushed Peter James' Centuries of Darkness, which argues for an alternative chronology for the Eastern Mediterranean and Near East.

There are some very real debates to be had about the Near East, specifically Mesopotamia, resulting from various king lists and chronicles with different sequences... before 1178 BCE. After that point, Babylonian astronomical diaries provide very clear, scientifically verifiable anchors. Egypt is less up for debate. The so-called Conventional Chronology has been generally accepted with very little alteration for over a century. It is supported by a wide range of evidence including stratigraphy, dendrochronology, written chronicles, and carbon dating.

All of the most widespread alternative chronologies for Egypt are heavily routed in Biblical narratives, mainly the stories of Joseph, the Exodus, the conquest of Canaan, and the united kingdom of David and Solomon. I wrote an answer compiling other answers for most of those events. The basic commonality is that there is little to no evidence for any of them. This includes James' Centuries of Darkness, which does make better use of scientific and archaeological evidence than some of its predecessors, but still makes the underlying assumption that the Israelites invaded Canaan and that Solomon presided over an opulent kingdom. In doing this, James and his co-writers use later evidence from the Levant to support their arguments for compressing the timeline of Egypt and Mesopotamia by almost 300 years.

They also make liberal use of dismissing archaeological periodization of Greece as unrealistically long without much supporting evidence or apparent understanding of how pre-historic Bronze Age archaeologists typically categorize material culture. They dismiss established linguistic evidence for converting Egyptian names to Hebrew in order to reassign the names of Pharaohs utterly outside of any conventional scholarship. Most comically to me, James argues that the similar style of Egyptian art, specifically shabti figurines, must indicate that they belong to the same time period. Archaeologically, this entirely ignores stratigraphic evidence that places different finds centuries apart. Visually, it simply ignores the fact that Egyptian artwork was famously conservative, applying traditional motifs and styles long after they reflected reality. For example: Narmer (c. 3000 BCE), Rameses II (c. 1250 BCE), and Ptolemaic (c. 300 BCE).

There is more to be said, but much of that was done when Centuries of Darkness was first published 1992. You can see several reviews on Jstor as well as this one on Researchgate for free. Some are harsh criticism, others are academically polite and point out that James et. al. did reopen the discussion of how tenuous some of the traditional dating methods are, which actually contributed to some very slight reassessments of early Egyptian history in the last 20 years. I'll use the concluding remarks from William A. Ward in the American Journal of Archaeology:

No further critique of this book is warranted since the same haphazard methodology and cavalier treatment of evidence pervade the chapters dealing with the Near East. Ther is little to commend their solution to the "dark age" problem. It is well written and certain essays - on the history of Old World chronological studies (ch. 1) and the Venus tablets (appendix 3), for example - are lucid and highly informative. The compilation of the evidence itself therefore, would have been a significant accomplishment. Some of the dark ages are slowly beginning to be illuminated... so that the universal solution proposed by James and his colleagues is not necessary.

And in fact, as Ward suggested back in 1994, some of the "dark ages" have been illuminated. In the 30 years since Centuries of Darkness was published, the Late Bronze Age to Iron Age transition has received increasing attention from academia and the work of scholars like Eric Cline. Centuries of Darkness is, by all accounts, a compelling read, which is why people like those users on Historum find it so appealing, but it is absolutely crucial to keep up with recent scholarship for a reason. In scrolling through those forums, I repeatedly found the same users claiming that the Bronze Age Collapse was "debunked in the 90s," when in reality they read one book that made an attempt and discard three decades of scholarship debunking that book.

Edit: In short, gods bless AskHistorians glorious mods because Historum certainly seems like it could use them.