Just want to reinforce that you need to backup the Brave-Browser folder to an external device if you are reformatting your PC. Your Brave-Browser folder (data) will not magically appear after formatting and reinstalling Brave. You will need to replace the Brave-Browser folder created with the install with the folder from your backup saved on an external device.
Even with a backup, you may lose data however, backing up the Brave-Browser folder and restoring the backup after your reformat is the best option for keeping existing data intact. Also, you may want to consider other things you may want to backup separately. This is a post with some guidelines and other information you may want to consider:
I hope your reformat and restore are successful! Good luck and take care. 