Travel in that direction. Once you see the village, save and quit to title.
Load your world in 1.16 and generate the complete village.
I couldn't reproduce it by just creating a 1.15.2 world and loading it in 1.16 so I guess you have to load some of the village's chunks in 1.15.2 and some in 1.16 for this bug to happen.
That's very specific so I guess I will just load the chunks around my villages before opening my world in 1.16.
Steps to reproduce:
Create a world in 1.15.2,
Locate a village,
Travel in that direction. Once you see the village, save and quit to title.
Load your world in 1.16 and generate the complete village.
I couldn't reproduce it by just creating a 1.15.2 world and loading it in 1.16 so I guess you have to load some of the village's chunks in 1.15.2 and some in 1.16 for this bug to happen.
That's very specific so I guess I will just load the chunks around my villages before opening my world in 1.16.