Colornote 3.9.82 SD card backup .dat files are not recognized after Android refresh
I fixed it! I was missing the .IDX file, so I made one with the same name as my .DAT file. Now I was able to restore my backup. (I also turned off auto backup) Thank you Android gods and Firelord.

PS1: I tried this before but than it didn't work, after reinstalling colornote again it did work. To everybody with Colornote: make backups!