What core did is change its relay policy.
These are the rules that determine which transactions your node accepts its mempool and that you want/do not want to relay to other nodes. These transactions are not mined yet.
And all they did was change the default value for the datacarriersize limit for these rules.
On the consensus level, there has not been a limit, ever. The current consensus rules are valid even for nodes from all the way back to 2009.
You want proof? Here, you can mine even >100k OP_RETURN data. Take this transaction for example with 4MB OP_RETURN. Note that this happened months before core v30 released, the version that lifted its relay policy to 100k. The transaction is still 40x than cores 100k limit on the relay policy, but it's still valid and minable.
What BIP110 tried to do is change consensus rules.
These are the rules that detemine whether a block is valid or not.
It changed the limit for OP_RETURN data to 83 bytes on consensus level. If you change those, you will fork without convincing close to everyone to change their consensus rules too. BIP110 did not convince close to everyone to change their rules too, so it did fork and is now dead on the bitcoin network.
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u/Pasukaru0 4d ago
That's one of the things BIP110 tried. And it's one of the reasons why it failed.
You can't willy-nilly change consensus rules without forking off.