dstke Should I try to roll back GOS?
I believe downgrade protection means you can't, unless maybe if you wipe your device.
You might try calling tech support for your carrier.
You might also try an APN reset of your SIM (though I have never done this): Settings, Network&Internet, click on your carrier under "SIMs", scroll down to "Access Point Names", "..." menu.
But if this is a disagreement between Fi and your phone there is a good chance you'll need them to resolve it.
Let us know if you find a solution...