"So from what I understand, when I use my tmobile phone over 4g,I don't have an ipv4 address that is routable."
T-Mobile is IPv6 only, you will have no IPv4 address assigned to your phone.
"So I am basically NATed to ipv6."
Other way around, your IPv6 connection is NATed to IPv4 via one of DNS64 or NAT64.
"Is Google including this kind of mobile traffic? I would guess that they are."
Yes, but maybe not in the way you're thinking if I'm reading your comment correctly. The IPv6 only portion is just INSIDE T-Mobile, when you need to leave T-Mobile to access services you will be using v6 if the services support v6 and v4 if the services support v4. Since Google is measuring this by how you connect to Google and most Google services are v6 enabled then you'll be counted as v6 properly. For the ones that aren't v6 enabled you'll be counted as v4 properly as they are measuring how you go over the general internet not how you traverse a private network.
If it shows that address while connected to WWAN only, then it's probably coming from 464xlat -- basically your phone synthesizing its own internal v4 network, with any outbound v4 connections being translated into v6 connections to 64:ff9b::/96 (or whatever your ISP's NAT64 range is).
464xlat works well for letting legacy v4-only programs access v4 via NAT64, but it doesn't help them reach native v6 hosts.
Normally this means if your phone supports IPv6 then you will actually be connecting with Google over IPv6 and if you can only use IPv4 then it's be tunnelled, v4 → v6 → v4. So the stats should be accurate.
So I am basically NATed to ipv6.
Is Google including this kind of mobile traffic? I would guess that they are.