Information is scarce on this topic, but here's a summary of some reading I did:

Hieroglyphs as a writing system tend to be used almost exclusively in formal and official context, at least from the corpus of texts that we have left. They are carved into temple walls, stelae, and so on.

Generally, the two "popular" ways of writing the Egyptian language were hieratic and demotic shorthand, which evolved as an easier way to transmit the hieroglyphs on papyrus. Hieratic definitely co-existed with the earliest days of hieroglyphs, and may well have evolved separately as a completely detached writing system. Demotic came much later, around the 7th century BC.

It's telling that in comparison to hieroglyphs, hieratic texts tend to be religious or diplomatic, and demotic texts tend to be personal or business-related. It seems that your average literate Egyptian would write most things in demotic, while priests and government officials wrote in hieratic, with hieroglyphs saved for the most important occasions. This is perhaps where the glyphs' reputation among Greek and Latin writers as being some kind of magical system came from.

There certainly exists "negative" sentiment in written Egyptian texts, such as the execration texts which are hieratic tablets listing the enemies of the Pharoah. You can see some of the curses brought down on enemies in translations that can be found here, although it's questionable if any of them get towards profanity.

However, Ashley Montagu's seminal The Anatomy of Swearing suggests an example (pp. 18-19) whereby a workman was recorded as having swore a false oath, which is the root of what "swearing" is. In terms of outright profanity though, I'm not certain whether we have any of it recorded. I found an unsourced reference to a vulgar lawyer's seal from the period in a book of "tasteless lists" but I wouldn't trust that.