I have one of those airtag bells, not bad. I originally got a water bottle bracket but the way my bars are it was a PITA to undo if you needed to replace the battery or make it soundless so I ditched the bottle bracket for the bell.
I did notice a difference with the airtag, which would make sense though. I had been storing my bike in our garage, 2 story wood & cement building with siding, no issies with tracking the tag (I get bored sitting in doctors offices, so sue me LOL) but when I put it in one of those steel storage boxes (think major company advertising them for moving) the tag completely & totally dropped of the grid, even if I was standing outside the box less than 5 ft away.
That makes sense though that the steel box was cutting the tiny little BT signal so no complaints from me.

I have hacked a couple of them to make them silent though, wasnt too hard for someone as clumsy as I can be, just watch the YT videos on it & take your time. And yeah, they can be tracked through the bell, probably would work better if I was in a city, but I'm not. Least its less likely for my bike to be stolen though, heheh.