This was discussed in another thread. There is no official procedure yet, but iirc someone is working on one. What I have been doing is turning off the camera in the app, after the camera is showing the off state in the app and the blue light on the back of the camera turns off, I then pull the power before removing the card.
I suspect since you were able to view the Playback fine until you removed the card, it may have been damaged when you removed it. Doesn’t FAT32 have a backup of the file allocation table? Seems I remember that from years ago.
Edit to add:
From the previous thread