Emma Turveyfoot wrote:is there a reason or explanation for t his?
The reason is that the "new" appearance is a much closer representation of how big vanilla Doom's menu used to appear on screen back in 1993. However, for quite some time now, GZDoom has had a different appearance and some mods will have been made expecting that appearance. So the reason is to make it look like Doom originally did.
If you look for "disable menu clean scaling" in the options and change the value, you can get back the older GZDoom appearance which might suit the mod that you are running.