TravelPass service throttled from 5G to 3G and H+ after using Google 1 VPN

[tgbiv]

I've been living in Japan since 2020, using Verizon TravelPass provided by my employer. 

I live in a fairly large city, and had access to a 4G network until I upgraded to a 5G (Android) phone in July. Since that upgrade I've been on 5G networks where avialable, and 4G when 5G wasn't available. My home has 5G coverage.

Late last week, I recieved a notification from Google reminding me that I had access to their free VPN service through my Google One account. Considering that I'm on an Android phone, I didn't think twice about trying the VPN feature just to see what it was about. I was curious whether it would consider my location to be Japan or the US, since using mobile data over TravelPass treats your phone as if it's in the US. 

After running the Google One VPN for a day or two, I noticed that when I left the house on Friday to walk the dog, as soon as I was out of WiFi range, the VPN disconnected and couldn't reconnect. Then I realized that I was on a 3G network, and in fact, had no Internet connection over mobile (roaming) data. 

I'd never seen this happen before. Even when going over my daily data limit I do not switch over to a 3G/H+ network. I just get slower data speeds.

I restarte the phone and it was still on H+,  dropping connection so frequently that I couldn't even load the Verizon support page. Since Verizon doesn't offer support over the weekend, I had three days to try restarting my phone and checking to see if I was back on 5G. I never did get back to 5G, or even 4G. I was stuck on H+ (when I could get any connection). 

Finally, today I contacted Verizon support. They said they'd "reprovision" my account to ensure I was able to connect to 5G. Unfortunately, they needed me to reset my Network settings, which means I've lost all my saved WiFi passwords. 

I asked why this would have happened and was given the standard response of "Maybe 5G and 4G towers were busy" which isn't going to be the case for three days, especially since my day starts around 3AM here. 

I asked if using Google One's VPN could have been a factor, and was told that it was possible, as "VPNs are not recommended." 

It seems to me that Verizon is using this throttled service to prevent people from using VPNs, even ones provided by the Android OS. I don't want to make a lot of assumptions, but there's a part of me that thinks this is a punative measure for blocking Verizon from gathering user data. 

I get a daily SMS message telling me when a TravelPass session will end. I didn't receive any SMS telling me that my service was being throttled for using a VPN. I think this is very sketchy.