I lost Dead by Daylight progress for the first time two days ago. Thanks to my backup I got all my stuff back, however I still lost my online rank because that is stored server side and cannot be backed up.
If you want to backup your save file read this Steam guide. I use this script myself, https://steamcommunity.com/sharedfiles/filedetails/?id=1109053921. The only thing I lost besides rank was 3 games worth of bloodpoints I had gained between the backup and loss of progress.