When I opened Evernote on my computer this morning, it suddenly showed an old version of a note from a couple of days ago. I still have the other notes that I created in the meantime, so it seems to be a problem with this note specifically. I did open this note on my phone before, so I am afraid that maybe something went wrong with the synchronisation because of this?
A lot of important changes are now lost, so I really hope it is possible to retrieve the version from yesterday. Unfortunately, I don't have Premium, so I don't have the option to look into the history.