This is more of an elaboration and clarification than a retcon concern, but, nonetheless, this is an issue for the
Warf Gossalizard and its descendants.
As pointed out
here it's unclear to what degree descendants of the Warf Gossalizard are endothermic, and how this endothermy is maintained.
The Hairy Gossalizard, while not noted as endothermic, has "proto-fur", which is mentioned as a cold adaptation, and stores fat in times of famine. The use of fat might be a clue on its metabolism.
The Warf Gossalizard is "slightly warm-blooded", has a fur-like integument, and lives in a tundra environment. It's not impossible for an ectotherm to live in the tundra, particularly if the planet's overall climate is warm, but in cold conditions it would require special adaptations, such as antifreeze compounds.
One of the descendants of the Warf Gossalizard, the Desert Gossalizard, retains its status of being "slightly warm-blooded", although it lives in a warmer climate and has less fur-like integument. That it didn't revert to ecothermy when it theoretically could have in just one step might suggest endothermy had been fairly well-developed.
(
This might be a useful source.)
By the submission under review, the Turquoise-Helmed Lizalope (if not earlier) it seems likely strong endothermy had been developed. Turquoise-Helmed Lizalopes are specialized for "running faster and longer" (relative to their ancestors) and are always on the move, and seem to eat constantly. Sustained activity like this in colder environments suggests endothermy.