Mine alerts (visual and audio bell), but doesn't tell you what song - just the artist, so you have to guess if it's something you want to switch over to. The same thing if you click the bell icon, then go into notifications (where favorites are listed) - it shows you the artist but nothing more.
I have a Scat Pack Challenger with 8.4, and my previous Ram PW had the 8.4 as well, and I basically lived in the favorites view. Because 8.4 allowed for 160 favorites to be stored, it seemed like my favorites view was always full of bands/songs I liked that were playing on the various XM stations. In this regard, I feel like the 12 inch uconnect in my '21 PW is a bit of a down grade. It's quite limited in the number of favorites you can store, and it takes a few clicks to get to the favorites view, and then once you get there it doesn't show enough detail to make decisions, so I've essentially stopped using the favorites option completely.
The uconnect system already has all the data it needs (items you like, whatever is currently playing on XM, etc) and the logical code is already in place to alert when something you like is playing on another station, so these fixes should be simple updates to the graphical interface (they just need to be prioritized by FCA).