See the reply by Brave team member @fmarier at:
‘Brave not starting anymore after crash - #15 by fmarier’
The section regarding “first attempt would be to delete these files/directories” ← to give you an idea of what may be removed. I would not wander past that list.
SPECIFICALLY re your issue, cache and log files may be removed. Some of the 000003.log files may be very/extra large? Some BB users have removed the particular 000003.log file at: /Brave-Browser/Default/Sync Data/LevelDB/000003.log and found improved BB performance.
(Note to self: 000003.log files ← this note to self is necessary because searching the Brave Community for 000003.log fails ← because the community search engine will NOT find what is located between beginning and ending back-tic characters!)
Your folder named Brave-Browser . . . Exit / Quit BB and Restart computer. Next, PLEASE MAKE A BACKUP OF THAT FOLDER before proceeding.
Finding files and folders - examples:
With BB NOT RUNNING: In a command line / terminal window, cd to (go to) that Brave-Browser folder.
Finding log files:
find -x . -type f -iname *\.log
Finding cache folders (I would not remove the cache folders themselves; only contents, following fmarier’s guidance):
find -x . -type d -iname *\ache