I am trying to avoid leaked content for The Owl House Season 3 and this extension has been working just fine so far.

This extension works very well if you use it properly.
Works great on twitter, reddit, and general browsing where spoilers are abundant.
Many of the complaints stem from its use on websites like youtube which are CPU heavy, but those can be whitelisted using the tag "youtube*" in the whitelist section.
If you still need spoilers blocked on youtube I use BlockTube, which works very well too.