G4AR - 5G was "perfect" until two days ago, now 4G only

I started TMHI around mid-March and I’ve been loving it since we moved from a fiber community to a rural home...I was afraid we were going to lose decent internet, but was pleasantly surprised by our consistent speed and latency (regularly 600-700 down/80-100 up w/20 to 50 idle ping).

Two days ago, in the mid-afternoon the 5G dropped out.  It wasn't subtle.  Gone.  Now, gateway shows "excellent" 4G and I'm pretty much at 8-10 down, 3-5 up and 100-200 ping.

Garbage.

I'm on my second gateway and SIM card...what's weird is when the replacement gateway finished powering up (with original SIM), it had 5G and speeds were back...I checked speed again in the morning and the signal was back to 4G. No amount of restart/factory reset would restore 5G signal.

Back on the phone w/tech support.  They say the towers nearby are "yellow"...said typically they would be orange or green, so not sure why yellow.  He said stop by a store and try a new SIM.

Popped in the new SIM and 5G!!!!!!  Yay!  For about 5 minutes...then, back to 4G.  Booooo.

I’m speculating that this was pretty much the same thing as what happened to the replacement gateway if I had been watching it more closely.

We use a lot of data and I wonder if the “de-prioritization after 1.2TB” means they drop you to 4G only???

Starlink will replace TMHI swiftly if they don't solve this "yellow tower and 4G only" thing...like, by Wednesday.  We both work from home and we can't have this happen...video conferences, etc. are mandatory.