There are some options you could try:
You can start Brave the following way from terminal:
brave-browser --disable-gpu
Additionally you could try to empty the folder GPUCache in your Brave user profile and see if the browser works again that way
And last but not least, you can manually edit the Brave config:
In your user profile there should be a JSON file. Find the setting for acceleration (“hardware_acceleration_mode”) and change it manually.