Bitcoin's OP_RETURN size increase in BIP-110 was a half-measure—10x the limit was still just 80 bytes, enough for a hash but not the actual data. Core 30.0’s soft fork locked in the new limit, but CSAM uploads could’ve slipped through prior nodes if miners tolerated them, proving decentralizat...

Yes. And it has been.

It seems yes... so the argument is that the bitcoin blockchain will have more CSAM after the 30.0 update?

Yes. It’s a pit, not a rabbit hole. Id recommend you look up the Bitcoin Explained podcast episodes 98 and 99 so you understand what actually changed.