In the manual backup UI there is option to encrypt them, but there is no such option in the automatic backup what happens regularly and on updates. (Or I haven’t found them.)
Could auto backups be configurable?
Ideally also frequency and excludes.
If you think it’s a good idea, you should vote for it. I did 
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More about Feature Requests.
You should be aware that encrypting your backups, while sensible from a security perspective, makes it a lot harder to recover individual files from a backup to repair a system without doing a full restore.
The backup first has to be decrypted using a python script you can find on this forum. You can not just enter the password into whatever decompression software you are using to attempt to read the file.
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