Yes, UA is flagging it on resolving the deeplink, but this is not new.

The tricky part (and I believe there's a thread [edit: different from that one]), is that UA is not flagging TPAC nonchangeable when following google flights. This part has caught me out a couple of times, causing much vexation.

Basically, for TATL, light fares get flagged; for TPAC, it's still the wild west.