Same issue I had as highlighted here Whatsapp and some youtube videos play but only show a fuzzy background and audio - #7 by mac1508
What worked for me was to roll back Brave to 1.88.138 version
I used Synaptic Package Manager to force a version. Search for brave-browser and use the “Force version” option to select the 1.88.138 version. I have then set the update manager to ignore the 1.89.132 version update.