It's often a matter of convenience. Dealing with overseas people is hard especially if there is a time difference. They probably don't explicitly decide to exclude someone but instead it's too much work to include the person.

I turned up one morning to find two of my coworkers in a project meeting conference call with the PM. Later in my weekly "all projects" call with the PM I asked why I wasn't invited. She told me it wasn't my project. She also doesn't think it's necessary for me to continue attending the weekly "all projects" meetings where we discuss progress and priorities on all the engineering projects company wide (across 3 sites).

I guess you really are being excluded!

It’s a good idea to start looking for a new gig, you never know, but better be proactive.

Having lived through that, it matches my experience. It's one of the reasons that I now fully buy into the recommendation of not being the only remote worker on a team.

One needs a truly exceptional team and manager to avoid being miserable in that situation.