Wyse 5070 as proxmox server with 32 GB RAM, memtest86+ very slow readings


Linux experience:
Beginner (Crawler)

Functional, energy-efficient, fully operational proxmox server for learning and experimenting at home.

Dell Wyse 5070 with Intel Celeron J4005 and 32 GB RAM
(According to the official specification, 8 GB is the maximum but according to internet users, 32 GB also works*)
*source: Dell Wyse 5070 – Home Server – FMDX.pl

During memtest86+ there is a noticeable slowdown in memory reading between 30-32 GB. Before 30 GB nothing suspicious is seen. The test ends without errors.
The exact same problem was noted by the author of the post I linked to above.

Should I somehow mark the memory in the 30-32 GB range so that the system does not use it? How can this be done in proxmox?
Alternatively if I stay away from exceeding 30 GB should I be safe?

Thank you for your help and time
Special thanks to Jay for sharing valuable knowledge