Looks like a lot of the issues you’ve described may just isolated and not general, to the 2020/2021 model. I have the same car RX Takumi picked up new las December and have none of those experiences other than initial wifi set up niggles. A Lexus technician eventually assisted me with the WiFi set up and it has been perfect ever since.
Not really sure what advice could be given, which dealership are you dealing with? As it may be worth approaching others especially with technology related issues . Hope you find a lasting solution to help you enjoy your car.