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?
In universe…I don’t think he does. “We” just don’t see it. A LOT of episodes have a line where some characters are TALKING about Odo shapeshifting “Oh he caught the Nassican Smugglers by turning into a three headed Karmdozian razor hawk”.
Out of Universe…sure the cost was a factor. Plus a lot of it looked bad…the horrible 90 computer animation.
*Though the BIG problem is: Odo is a Demigod. Just like Data. So the Writers have to forget about him. Odo is immune to physical weapons, so they need to forget that. Odo can’t be knocked out with the ‘magic TV off button’…but he, of course is…wink wink. Odo can escape and spy easy. And win every fight. And Remember Odo can shape change PERFECTLY into anything except a humanoid…