What
Hooks (scripts that run at certain points and can attach extra 'context' information) previously had their context arrays checked to ensure every entry could be traced back to something a prior hook in the chain had actually added. That lineage check has been removed. The validation now only checks that context values aren't non-list, that entries aren't empty strings, and that the total length doesn't exceed the character limit.
Why
This loosens what hook-supplied context is allowed to look like, dropping a rule that previously required an unbroken chain of attribution between hooks; the practical effect is that a hook's context is no longer rejected purely for not matching what an earlier hook passed along.