is "dieses" correct here but "dieser" and "diese" incorrect because we don't know what the subject actually is, so we don't assign a gender to it? could "dies" work?
All forms of "this" (dies/dieser/diese/dieses) work
tell that to duolingo
Can we say “guter“ in place of “besser“?
Of course not! It's bad gramar
How about "Es ist besser?"
Duo = FAIL %#*&^ this program is trash sometimes.