We have quite a few questions about spell effects and what happens when their target enters a state where they could not have been targeted by the spell in the first place:
- Can Polymorph end spells that require the target to be humanoid?
- Is a spell suppressed or removed when the target temporarily becomes invalid? 
- Does the light from Branding Smite persist after the target dies? 
- What happens if modifications are made to the base entity while it is under the effects of a suppressed True Polymorph?
- Is it possible to possess a non-humanoid creature with a combination of True Polymorph and Magic Jar?
- If a creature was flying via the Fly spell and dies, does it continue flying?
- Would the Animate Objects spell end an ongoing spell affecting the targeted object(s)?
- Does a Huge Object that has already been Animated continue to be Animated if it is Enlarged to Gargantuan?
- Can a willing creature targeted by the Animal Shapes spell choose to return to their normal form before the spell as a whole ends?
- What happens if polymorph ends while under disguise self? 
A bracketed number indicates that the question has been closed as a duplicate of a question in this list. For example, question 2 has been closed as a duplicate of question 1. Note, I made all of these closures and they are, effectively, what brought me to ask this question.
Notably, the very last question is closed as a duplicate of the second. Is this correct? Is that the only one that should be closed or are there others as well?
Note: I left out a few related questions that are, to me, clearly not duplicates despite asking about similar topics because they hinge directly and explicitly on a spell's specific wording. For example: