I’m confused as to how a content blocker could cause this. Could someone more knowledgeable than me elaborate?

Meta is using some fingerprint ID to recommend connecting accounts . - you don’t see the accounts itself(beyond the name ) unless you are able to login verify ownership.

The WIPE/privacy extension developer is using a pre-existing(hard-coded or generated) fingerprint to “mask” the user from meta .

Meta implemented a quality of life feature powered by the ability to set cookies and track you across the web of course and help users with forgotten accounts to unify them - but not a security issue you cannot do anything unless you are proving access governed by standard auth protocols ; the extension developer’s hack to mask created a broken experience because of the reused IDs.

Adblockers can create unintended effects , it is hard to reverse engineer complex platforms like meta and also hard to keep up to date with billion dollar companies code updates by small indie teams of volunteers ; doesn’t mean we shouldn’t use them, just be aware that it may happen when enabled