They could be considering the new high end display a different product rather than a refresh (for marketing purposes at least).
I recall the XDR being announced alongside the last Mac Pro redesign. No new Mac Pro yet, so maybe they’ll announce the new large display whenever that is announced?
”Studio Display XDR replaces Pro Display XDR and starts at $3,299 (U.S.) and $3,199 (U.S.) for education.”