Just a heads-up as many users in that thread are reporting Android Auto issues with their Pixel 8 and 8 Pro phones, and the response by the Android Auto team there is to file a bug report.
Do you also encounter issues with Android Auto with the Pixel 8/8 Pro?
I paired my P8P to my car last week and was able to use it. Today, it doesn't even appear to try to connect. My other vehicle, which has the motorola AA dongle in it, works a-ok still.
My P7 no longer connects to the first car either, so, at least for me, it's not just pixel 8 specific.
I've had issues with it every time I get a new device. I don't have the 8. I have a 7 Pro but I had issues with that at launch and the Note20 Ultra prior at launch and the Pixel 3 at launch. I've typically had to wait a couple weeks after I buy it for everything to get figured out. The only one I've consistently had issues with is my 7 Pro. It's almost like it won't work with my older car anymore. It works sometimes and then other times disconnects and refuses to connect. I blamed it on tensor(uneducated guess) but it's been a year now and my issues have mostly disappeared.