Poor _receive_ signal from clients on Wi-Fi

While trying the BE14 card on the latest OpenWrt snapshot I noticed the signal quality of reception from the client to the router dropping disproportionally as a function of distance compared to transmit. My client is a MacBook with a Wi-Fi 6 NIC at 5 GHz (80 MHz channel width).

In close proximity to the router I get Rx/Tx rates of 740/706 Mbps. 3 meters in direct line-of-sight gives me 710/280, and at 5 meters it goes down to 704/95. The signal strength of the client as seen on the router also degrades all the way to -67/-68 dBm at 5 meters.

I have no reason to suspect the antennas (Taoglas GW.52.A153) or pigtail connections inside the router. 5 GHz band is virtually clear of other wireless stations where I live. A Qualcomm Wi-Fi 7 NIC with the same Taoglas antennas exhibited a similar behavior, albeit not as extreme as the laptop.

I’m puzzled by those results. Could there be any software tweaks for OpenWrt to improve reception that I might try or is it completely normal and expected for client NICs to have such a poor Tx signal?