RF loss / failsafe when flying over water

Hey! It has been a while since my latest post on this site but I’m here again with another weird issue.
I have been flying my drone for some months now and everything is fine, some weeks ago I tried to fly over the sea to film the hotels near the area that I live in and strangely the drone failsafed and started returning to home, only being 200 meters away from me, over land it can fly for more than a kilometer with no issues. Then some days later tried the same in another location, pretty far away from any antennas or such things but same result, that time a little bit further but still ended up in a failsafe.

Tried to fly the mavic mini 2 there (not mine) and no issues there.

Can water block frequencies even when the drone is high (above 50 meters AGL / ASL)?
Does anyone of you have similar experiences?

I’m asking because this weekend I’m planning to fly over water again, is it safe? Or is there a possibility of a flyaway or similar? Why does it failsafe all the time?