Player Unhappiness, wanting to move clubs!

Right, im in season 2021 with hibs and have got them into the champions league season after season but all my players are "frustrated at not being allowed to move clubs" etc. I wouldnt mind if this occasionally happened but even with players i have just bought who say they welcome a fresh start, when the first bid comes in after a few months of them just joining me they become unhappy and want to leave the club. I cant keep a team for longer than half a season.

Also, they say they want to move to a bigger club and then accept offers from teams in my division who finish lower than me. WHats going on!?!?