Okay, so I've got a TP-Link Archer TX3000E (pci) and an ALFA AWUS1900 (usb).
My router is a Sagemcom F@st 5260.
(forgive mefor being terse, but I'm omitting the presentation that was somehow missing from my previous attempt)
On windows and debian, both devices connected to my network simultaneously, or with one in monitor mode, or with the two on different networks, vpns on and off, any sort of thing you might do works.
On Arch when the (usb) is connected to my network it does...SOMETHING...that my router resolves by blacklisting everything that was on the network at the time of the thing. Because the 2G is visible on the available list of APs and the 5G is not (which is what I was using at the time). Also my phone was disconnected from and could not see the 5G. Reset router and it's back.
This happened most recently with only the (usb) connected to my network after 3+ days of functioning normally.
I'm glad to provide outputs from any digging in anyone might wanna see.