I have the 1st Gen charge cable and get 40A. New cable from 40A - 32A. New Wall charger 80A - 48A. Really dont want you fast charging at home for some reason.
None of it is anything close to fast charging as far as the batteries are concerned. It's quibbling about 10-20kW when the batteries can take about 100kW. Any kind of home charging is basically slow.
I do see the reasons for the changes, and I agree with the mobile connector changes but not the wall connector changes.
Regarding the mobile connector:
There has been a long time exception in electric code where you are allowed to put a 50A outlet type onto a 40A rated circuit/wire/breaker. A lot of ovens are installed that way. There just isn't a 40A outlet type, and if a 40A rated appliance is going to be plugged into it, they allow that specific kind of mismatch. So it is not entirely uncommon to find these kinds of outlets in some places at houses people may visit. So someone plugs their charge cable into it, thinking it's a 50A circuit when it's really a 40A circuit with thinner wire, and......hopefully the breaker pops before Bad Things happen. So I get Tesla wanting a bit of CYA so they aren't blamed for meltdowns and fires from people accidentally discovering these weirdly wired outlets.
That's thing 1. The other part of it you can kind of see in the products they do still offer. The "Corded Mobile Connector" is literally a 1st generation UMC, except the plug is permanently attached, so it doesn't have that changeable connector with the pin and sleeve mechanism you can slide on and off. Those kinds of sliding connectors are a more resistive weaker connection than something permanently wired on, and running 40A continuously through that is kind of iffy. They did have some troubles with those connections melting a bit on people's 1st gen UMCs. I've been running mine for 6 years with the current set for about 31-32A just to keep it cooler and not have that problem. So I think the smaller 2nd gen UMC is just less current and heat with those changeable adapters, so less likely to have problems. So I do stand by the UMC changes.
The wall connector stuff, though, is directly related to chopping off the onboard charger capabilities, and I do hate that change. The hardwired connections can handle those higher currents, so it's not really for safety issues. They are just cost cutting something they think most people don't need, but not offering it as an option is really irritating to the people who do need it. So yes, they are basically just dumbing things down and causing some people some difficulties.