Proton GE prefixes can not have dotnet 40 properly installed, I think it was also the same for other version of WINE, I think they were layering the dotnet40 or something to make it work.
The reason why Epic's version of ESO stopped working for 2 weeks is that EPIC and ZOS made the files mandatory require dotnet40 to work.
With WINE 10.5 staging, devs made some changes to mono and the WINE itself to at least have that damn thing be properly installed, or so I was told. After installing dotnet 40 into a fresh prefix through terminal command, for some, the game ran properly with the 10.5 WINE. But it did not for me, I had to change runner to GE-Proton9-27 and then run the game again and then it worked.
That is the reason I was asking my question, someone who tested, said that with new changes, I should have been able to directly play with 10.5 staging WINE without any modification.