K9 on OnePlus 9 Pro

The version of K9 on the Play Store did not work properly on my 1+ 9 Pro. Android didn’t install it when setting up the new phone from the old, when I did a manual install I was watned it was for an earlier version of Android: installed, it seemed very prone to crashing (while importing settings, and after another try when entering the account password), and there were duplicate Trash, Sent, and Outbox folders.

When I installed the latest beta version 5.734 and reimported the settings, I got a second and third version of the same account, the third without duplicates - so I removed the superfluous accounts and all seems now to be well.
Thank you. For a few moments I was worried I was going to have to find a new mail app.