This made me leave Brave, recently returned and still is on.
Initially Microsoft Edge also did this, back in January, Edge stopped doing it so I thought Brave would too. But no.
For no reason I can tell, Brave ends at some point hogging the CPU, bringin CPU usage to 100% with Brave using up majority of it (65%). I think once it stopped after a long while on its own, but generally I close it before that long.
Windows 10 Home 64-bits on an Intel Core i7 4770.