I don't think there is actually a specific maximum OP_RETURN size that on its own makes a block invalid. I think the limits you're seeing like 75, 80 and 83 bytes are standardness rules which actually determine if a transaction will be relayed by most nodes on the network or not. A transaction that exceeds these standardness limits should still be valid if it adheres to the network's consensus rules.

In my opinion I think If a miner includes a non-standard but valid transaction in a block that block remains valid and will be accepted by the network. So basically the true invalidating limit for an OP_RETURN transaction is the maximum block size and weight which is around 4 MB for SegWit blocks. If including an OP_RETURN or infact any other data causes the total size of the block to exceed this consensus limit I believe that's when the entire block becomes invalid.