A couple other things I've noticed having to do with "promoted content":

1. uBlock origin seems to block ads in the normal web client, but not in the mobile web client (in desktop FireFox as well as mobile FireFox).

2. Mobile twitter client lacks the drop-down menu where you used to be able to choose "I don't like this ad".

Now that I look at it, though, that menu on the main twitter web app doesn't have that option any more, either. You can "report this ad", which isn't quite the same.

To get to the same menu in the mobile web app, you need to tap/click the add tweet, then choose the more options icon.

The normal twitter web app has now added a "dismiss" option on mouseover.

FFS, there's no consistency of interface across the three at all!