We need a BlockBreak Event

Concerning, this will be a giant performance burden

A player block break event might be a good idea, we have the block attack one right now.

my dreams of having a block break event is close

A player event for breaking blocks makes some sense.

However a raw setBlockState event is probably not contextual enough. Even then a full ChangeBlockStateEvent would require almost every mod which uses it to fail as fast as possible.

Concerning, this will be a giant performance burden

no not really, fabric events are fast enough, and really, no matter what u do, it can't possibly be worse than TACS, 99% of time in setBlockState is spent waiting on chunks anyways.
But a PlayerBreakBlockEvent is probably more useful, so meh

Either way these types of events if they are Cancellable need a sort of post/after event for mods to listen to if notification of block changes are needed

Yes ofc

A player break block event based on packet input is definitely useful. The mass block change one isn't as needed imo and has more potential side effects.

shameless plug, u don't need any packet stuff

Oh look this has been merged