Fabric Loader 0.10.8. Without Pandemonium game loads normally. If one of the mods with bold names isn't present then the game loads normally too.

Mods:
fabric-api-0.28.0+1.16
modmenu-1.14.13+build.19
requiem-1.3.0
requiem-pandemonium-1.3.0
[1.16.4]+Flight+Rings+1.4.2
accurate-block-placement-1.0.8
bedrockify-0.2.0-1.16.2+

crash report - https://hatebin.com/jwndniadfc
latest.log - https://hatebin.com/byynzcwzwu

Preliminary report :

• The crashing mixin is this @ModifyArg in Requiem
• Bedrockify has a @Redirect in the same place as Requiem, likely cause of the conflict
• Flight Rings has no mixins, can't be responsible
• Accurate Block Placement doesn't seem to have a conflicting mixin, probably not responsible
• Pandemonium doesn't have a conflicting mixin either, probably not responsible

Since the issue only arises when other random mods are present, I assume it's because they alter the load order.
In your log, Bedrockify is loaded latest, so I assume it works when it is loaded before Requiem.

I think I should be able to fix it, but it probably wouldn't hurt to inform the Bedrockify author.

Edit: it crashes when Bedrockify's mixin is loaded after Requiem's. I think I got a fix.

Can I get the crash report ?

Yes, sorry I forgot somehow

Should I post this on Bedrockify, Flight Rings and Accurate Block Placements githubs too?

Ok that's indeed a weird bug, thanks for the report. It's some kind of mixin conflict, but I can't yet tell what's the cause.