I've run into a similiar issue when upgrading to a newer version of react-native (0.77).

For me the modal ended up in the top left corner when the Modal component was defined without any parent view (some of my problematic modals were defined basically at the App.tsx level).

Wrapping the modal with View component ended up solving the issue. You can even use the new display: "contents" on the view to not mess with the existing layout and only provide a wrapper for your modal.