Secondary monitor taskbars can't have certain settings which is why the content of the menus differs.
Hmmm, ok. Didn't know that. These are MS taskbars, no DisplayFusion, etc.
As for the style, did you perhaps enable some registry key to remove the dark menu from the taskbar at some point? I think that only impacts the main monitor menu hence the mismatch in styles.
I am using a right click enhancement app. My issue was more about content than style. Thanks Neil. Appreciate the quick response.