Lol rekt. Copied from Twitter:

A bug was found in the ordinals protocol that caused ~1,200 inscriptions that should have been valid to not get included.

The first of these "orphan" inscriptions happened just before inscription number 420,285. The bug was caused by the ordinals protocol only counting inscriptions that were in the first input of a transaction.

So far ~1,200 inscriptions were not in the first input in a transaction. This leads to the question of what should be done about this "bug"? From the people I have talked to about this, everyone seems to agree that we need to upgrade the protocol to count inscriptions made in every input of the transaction so that we can do cool things with PSBTs or inscribe multiple inscriptions in a single transaction. The question being debated is what should be done with the orphan inscriptions and the numbering of existing inscriptions after 420,285.