I am using Firefox for a long time. And I always disliked how Bangla language fonts render in firefox. Current "Vrinda" font does very bad job to render Bangla language. On the other hand Noto font always works like a charm. Doesn't need any tweaking or manual intervention.
Requesting the Mozilla team to make Noto fonts as the default Bangla font. Which probably render Bengali font as best. This is probably an example link for how bad Bengali font render.