No, the Fast ring is NOT 20H2 - the Fast ring is an unspecific development test build. Not everything in this build will be in 20H2, some things will only be in 21H1 or beyond, and others will never get into any release.
Did you or someone else post something about the path 20H1 2004 is taking, i can remember some stuff about it.
That will take a while that people understand that rs_prerelease is only the test branch. That’s the same with the 1909EP, took a while but now everyone knows it. (Hopefully)
That would be up to BattleEye surely? I believe MS have made it clear they believe it's up to them to fix it.