Thank you for your answer nc50lc!
I have a few more perhaps stupid beginner's questions:
I only have one wallet.dat file, so not several wallets. I use this as long-term storage for my coins.
I have passphrase encrypted my wallet and always make backups of the wallet.dat if I generate a new address.
If I now convert my wallet into an HD wallet or a Descriptor wallet and something goes wrong, can I still use my old wallet.dat file again if I copy it to the wallet.dat location via linux termial?
Should I update my wallet.dat at all? I hardly ever generate new addresses. Or do I have a disadvantage if I leave everything as it is?
What would you recommend?
Thx a lot
Michael