In T326298#8504651, @jsn.sherman wrote:

We had an issue like this before when a user was getting stale my library content. I'd recommended double checking @Fehufanga's authorizations and account status and asking them to try from a private browsing session if everything looks okay with the account.

In T326298#8501309, @Samwalton9 wrote:

Sorry that you're experiencing this. I can't reproduce this error in Chrome 108.0.5359.124 or Firefox 108.0.1 on MacOS; I'm able to both add and remove favourites successfully, with around a dozen favourite collections.

If you right click the page, click Inspect, and open the Console tab, does any error appear when you attempt to click the favourite button?

This time it looks like the edit count doesn't increase by twofold. The sections being copied appear to be identical to the previous runs.
As a temporary fix, a {{bots}} template was added to the page to disallow IABot from editing the page.

After replacing the table with the version from the English Wikipedia, IABot did another run and it went fine: diff.