Unfortunately, I was a little euphoric about getting the second USB port working with the newer kernels. Today, after a lot of reboots and three days uptime, I noticed that my second USB port was not working any more. I do not know if it simply stopped working or was not available from the last boot. At least, rebooting brought it back again. I also did a lot of testing with moving the system to an USB SSD which also failed or succeeded to boot randomly (power issue excluded). So, be aware that my proposed solution to use kernel 5.11.18 or 5.12.6 is only a workaround and might not be stable.
