When a Zombie starts shaking after 30 seconds to indicate it is drowning and is then removed from the water, it no longer continues to shake and become a Drowned.
-Submerge Zombie in water
-Wait until it begins to shake (30 seconds)
-Remove Zombie from water
-It stops shaking and no longer drowns
This is intended behavior per MC-227250 being valid. Judging by your description, it would seem that that issue has been fixed; it will be resolved as such once the fix version has been identified.