It always used to be that some apps prefer content:encoded if it’s there; and some apps who don’t want HTML will prefer the description field if there’s a choice.
Putting the same content in both is wrong. So - “deprecate putting the same data in both content:encoded and description” would have my vote.
In this case, I think more testing is required (again). Podclock, a podcast testing feed I have, might need to need checking.