"tmobile diagnostics keeps stopping" galaxy s20 pop-up

S21+ owner here. Like others, disabling the Diagnostics Metrics seemed to work for a while, but it came back with a vengeance. After coming back to this forum and seeing no solutions, I tried this:

1. Disabled all app’s permissions except "Phone" (it wouldn't let me disable "Phone").
2. Cleared the app's data (under Storage).

Since then, no more pop-ups (yet?). Good luck!