Epic Launcher does not support cloud save so yes, all games that are on Epic Store are stored locally so any type of corruption or deletion of a file/game of some sort will be permanently lost unless backed up to another file. I stopped playing myself (unless cloud save is finally supported), just like you, I had like 3-4 classes maxed out until one unfortunate day my pc crashed when starting up the game and corrupted my save file so I lost everything.
I play on PC, I was Level 151 with most weapons upgraded... now all back to lv1.... I really hope I could get my progress restored. Definitely not going to touch this game again until there’s a solution. If not.. at least allow me to get a refund, this is absolutely frustrating since I can’t even play the game since I fear it’ll happen again..