Ran into a similar issue with extracting files from an iOS/iPadOS app when trying to export the .realm data from in Realm Studio to a .csv file...

Here to add that as of July 2025 using Realm Browser (an app that is no longer updated) works just as Apta says (on an Intel Mac running Sequoia 15.5).

I opened the default.realm file I was working with in Realm Browser, and was asked for a valid encryption key to open the file. Instead, I opened up a file that Realm had created in the same folder called "default.v7.backup.realm", which worked just fine. From there, it was easy to export the .csv file(s) for the class(es) of interest.

Thanks for the assist, Apta!!!