This is why when Garmin Connect has outages you can’t sync the watch to the phone, it’s a pretty bad architecture. It should sync to the phone without internet or any services and then use internet to sync from the phone to the cloud.

It's utterly bizarre. I was impacted by that outage a year or so ago and they claimed that they were going provide offline syncing in the future but I still don't see it. It seems the flow is Watch ->(Bluetooth)-> Phone ->(LTE/WiFi) -> Garmin Cloud ->(LTE/WiFi) Phone. There's no reason for the Cloud step other than that Garmin wants your data but the sync won't work without it.