It was more common than you might think.

It is for example documented that Erich 'Bubi' Hartmann (German WW2 fighter ace, credited with 352 kills) had to force land his BF109 a total of 14 times due to combat debris causing mechanical failure and related issues.

With some simple, overbanalizing math, that brings us to 1 debris-induced-landing per 25 kills.

Keep in mind WW2 era planes, while mostly a metal monocoque construction, still have dozens of other small parts which can detach under machinegun/autocannon fire, especially under the german MG 151 Minengeschoss shells. Control surfaces, flaps, external bomb racks, extruded landing gear, all very prone to detach at high speed if damaged. Another big issue is damage causing oil to leak into the exhaust - continue flying on a damaged plane's six and your own canopy will be practically impossible to see through due to oil splatter.

Sources: Toliver, Raymond F.; Constable, Trevor J. (1985). Holt Hartmann vom Himmel!