Which one? There a dozens commonly used ones

Dosbox Staging has one CRT filter which is the one I’ve used. The town wall graphics (edit: In might and magic book one) get completely messed up with it. It is possible the bad effects for each of the 4 games mentioned was caused by a bad CRT filter.

That said it would’ve been better to include screenshots which do use the CRT filter. I have played all 4 of these games with and with Dosbox Staging’s CRT filter and they all have had black lines obscuring the screen. Not having it enabled, on the other hand, the games looked like these screenshots.