Suggest that you try to keep the workload light for a while, meaning if you must use Tabs as a matter of habit/practice, keep that reduced to a max of 10 Tabs per Brave Browser window.
Do not yet use Brave Sync, in order to, for a while, reduce workload.
In a Brave Browser New Window, go to: ‘brave://flags/#use-angle’ and try ‘OpenGL’ instead of ‘Metal’
And for ‘brave://flags/#enable-gpu-rasterization’ - set to Disabled
And for ‘brave://flags/#enable-zero-copy’ - set to Disabled
You certainly can test each of those, one-at-a-time.
Exit / Quit everything and Restart the Mac.
Take a look at Brave Browser Task Manager window display:
Brave Browser Task Manager window that displays column titles:
→ Task | Memory footprint | CPU | Process ID | Image cache | Script cache | GPU memory | JavaScript memory (<-- that creeps up)
When you add columns in the Brave Browser Task Manager window, they may not appear in that same arrayed order.