> // Check for any random auto-added <br> elements, and remove them.

> // These get added by the browser when we undo the above mutations

> // and this can lead to a broken UI.

This made me laugh out loud. Browsers!

Until here our approach looked quite similar. Leave the observer connected during reverts and avoiding double-peocessing using .takeRecords never occurred to me, I always disconnect it. Maybe some of these brs are causing chaos…