T-Mobile had this issue 5 years or so ago where the IMS core went down due to fiber issues at one of their major backbone providers (pretty sure it was zayo).

As I've said elsewhere, never underestimate Verizon's incompetence. A couple years ago they shut down vtext service which also happened to host their UAprof's for most Android phones. Without a working link to these descriptors, those devices would download any MMS (pre-RCS picture messages) in compatibility mode at the lowest resolution.