I'm gonna cut mine back to 40amp, and see what happens. If that works for a while I'll bring it up in 2amp increments and see where I start having problems.
Since my charger is nacs and my Rivian is nacs I don't think this is an adapter problem for others. This is some kind of Rivian issue with the Tesla wall connector.
I dropped the amps down to 40 for several days without issue, and then went to 42 amps and did a pretty lengthy charge session last night with no issues. I think I'll jump up to 44 amp tonight and see how that does for a couple nights.