I know this is not helpful to your immediate issues, but here are a few suggestion to prevent it from happening again

• Don't store important data in any default folder. Make your own folders, name them something so you know its yours and not a system folder. I like to start my folder names with "AA", so they show up first in the list.

• • I'm honestly surprised SD maid cleared out the backups folder. I'm speculating here, but I think that backup folder is intended for apps to leave their backup files. All of your data, which isn't associated with an app, got flagged as "leftovers" from a deleted app.

• Backup off device. If SD maid didn't delete everything, a drop in a pool could have. The general rule is to have 3 copys. 2 in your possession (phone, computer, home server, USB stick, etc) and 1 off site somewhere (cloud, at friend's house, etc).

• • The easiest way is to use a cloud provider like drive. Download the sync app to at least 2 devices and enable "keep offline" for the folders. However that is not necessarily the most secure. I like synching to sync all my folder to a computer. It has conflict protection, so if I happen change a file on different devices, it won't save them over each other. The final method that requires the least setup, but the most discipline is a USB drive to copy your data periodically.

• For the data you described, it sounds like you would benefit from storing it all in password manager like KeepassXC. It encrypts all of that, and makes cloud storage a safer option.

Good luck with recovery.