FWIW … from PC using wAP AX as AP and Hex Refresh in between towards RB5009 as router with iperf3 container … I was able to get 900Mbps.
Hex wasn’t even sweating.
But that’s with Hex Refresh in managed switch mode (read: VLANs being used) NOT using ether1 as uplink !
In that same config using ether1 as uplink, speeds go down drastically (peaking sometimes towards 500-600Mbps but rarely more, average 363 Mbps).
So pay attention to block diagram to decide what you connect where and what you use it for.