openrtb.pair.unsupported_version
What it means
Request/response cross-validation was requested for an OpenRTB 3.0 pair. The pair checks (impid, mtype, seat, deal, currency against the originating request) are built for the 2.x object model, so the response was validated on its own instead.
Why it matters
A silent skip would let a green result imply the pair checks ran when they did not. The warning marks the coverage boundary explicitly so a CI gate cannot mistake absence of findings for cross-validated coverage.
How to fix it
Nothing is broken in your payload. Validate 3.0 requests and responses individually; if you also run 2.x traffic, pair validation works there in full.
Check your payload
Paste a bid request or response into the tester to see whether this code fires against it, or gate on the id in CI with the CLI: the id is stable, wording is not.
Back to the full diagnostic code reference.