It's not something to worry about. What Epic is looking for here is digital input to filter out native m/kb users into separate lobbies. That ended up backfiring big-time and was reversed because Sony has licenced third-party m/kb adapters, as well as a slew of assistive technology devices that got caught in their net.
What's left-over from the digital filtering sage is the popup warning, which also appears in the inventory when using a d-pad, which is digital input.
Either use SAB on XIM, or just ignore it.