Back in the day on TrekBBS (alas, I cannot find the original post), someone pointed out that Odo shapeshifts less and less often as the series goes on. It was never a super frequent thing, but it occurred more often in the earlier seasons, but, even accounting for his time as a solid in Season 5, he seems to shapeshift less and less in later seasons.
What reasons (in-universe and real-world) might there be for this? Was it just a budget thing? Were the writers using it as a “trick” (writing crutch) earlier on? Are we supposed to believe that Odo is trying to assimilate, or reject his Changeling heritage?
This is what my head-cannon is as well. Later on during the Dominion war people were already lumping him in with the founders and because he’s a shapeshifter as well. I’d imagine when the founders are shapeshifting to infiltrate the Federation, it would make you hesitant to do so in public.