I sold my 2015 Model S 70D with 198k miles with about 12% degradation.. in the 2 years I owned it, I Supercharged over 1000 times and charged to 100% almost daily without any accelerated degradation.
I suspect Rivian is pulling a Tesla in this regard and only displaying the energy delivered to the battery rather than energy pulled from the station for battery charging and auxiliary use.
There is no other logical explanation to the charge curve than a 350A limit, especially given that there have been multiple reports of 180+kW on the R1T.
I guess that would be the prudent thing to do, but it's very unlikely an entire EA station would be down. I've roadtripped my VW ID.4 around the country and never had an issue charging.
I suspect @rhuber is spot on - both Model S Plaid and R1T use a peak 450V pack and would be around 430V at 50% hitting ~150kW as both demonstrated with a 350A limit. Trying another station is key here. Hopefully you can make that happen, @TFLtommy. Also, if you test again, I think doing 5% or...