There is a farm design by hex gaming for trident( https://www.youtube.com/watch?v=ftJfvMPSG1k ). In that design after using the farm for some time, suddenly the drowned are no longer affected by movement of water and stay stationary rather than getting pushed in the direction of water by water( https://drive.google.com/file/d/1_K4dmme4TCxCfkPPB7HMKStydarX4PSc/view?usp=sharing ). They show slight movement in direction of water after few seconds and are getting stationary again. 

After 1.18 update the feature of external storage was removed from game and all the progress are saved in the app itself. But they are saved in such a manner that the app cleaner assumes it to be a cache and deletes it while deleting the cache of minecraft pocket edition