Very weird signal strenght readings!

Hi!

Hope you guys can help me make sense of it. Either I'm reading it wrong or something is very weird around here...

So I have a RPi4 with openWRT playing the role of router, and two identical Netgear Wax202 routers to serve as APs, both with only 2.4GHz enabled.

One AP has openWRT, and the radio is set on Mode AX, Channel 1, 20MHz. Max transmit power is set to 13dBm. The status on its own Wireless Overview fluctuates around -52dBm.

The other AP has stock firmware, 11AX enabled, auto channel (but also 1), HT40 (even though channel analysis says it's 40MHz intolerant) and 50% transmit power.

In the other room, my phone sees the connection on both as 3/4, fluctuating to 100% some of the time.

.>>> now to the weird part. I'm at the 2.4GHz "channel analysis" page of the RPi, which is sitting about 30cm (1ft) from the APs.
While openwrt AP reads -26dBm, stock AP reads -85dBm! Weaker even than my neighbors' (-48~-63dBm)!

What's happening here???