class-wp-hook.php on line 288

Reinstalling core should fix this issue. This is more than likely related to a botched update from 5.3 to 5.3.1.

Edit: To clarify, 5.3.1 included some hardening with relation to kses (specifically wp_kses_bad_protocol()) as noted in the release post.

In the error output above, a core file was referencing a core function that didn’t exist, which tells us that one core file was updated but another one elsewhere was not. So “botched update” is the conclusion.

As for why the update didn’t work, your guess is as good as mine.