"Mobile Broadband off" icon looks like "Mobile Broadband" active with bad signal
On my current Gnome 42.0 desktop on a Debian laptop using 4G, it is hard to distinguish (by icon) if my 4G connection is active or not:
This is how it looks like when NOT active:
This is how it looks like (look in topbar, and in menu (not text)) when Active (but reception is not so good):
I think it was more clear in earlier versions: like with the wifi icon above there was a stripe-through