I did some testing. Here are the results:
Qubes 4.0 on Kernel 4.19 => Works OK. Freezes are very rare.
Qubes 4.0 on Kernel 5.4 => Freezes regularly.
Qubes 4.0 on Kernel 5.15 => No problems at all.
Qubes 4.1 is another story. They for whatever reason did not compile ath11k driver into the Kernel of the installer. So, in order to boot the 4.1 installer on T430 with Atheros Wifi Chip, the Wifi switch next to the SD card slot must be turned off.
Conclusion: T430 hardware is not the problem. Qubes Kernel is.