My environment on Mazda MX5, It is not happened normally. but I have experience to NOT connect CarPlay twice. at that time, I have remove/ON cable, then recovered without any issue. Firmware is 2021-03-06
Use sync mode : normal and
and use "Background mode" you will get nearly zero message of Apple Carplay Failed
Since Background mode will hide the connection screen and wait until usb connection establish without usb timeout unlike normal mode.
With background mode you can use 0 startup delay as well.
Test on my Mazda 3.
Now I just wait until hourly reboot getting fix, everything will be perfect.
PS. I've test the Compatibility mode and it doesn't work well either.