@Der_Rayan_M there is no need for such a restriction - the players of which are generated by Nordeus ("factory mutants" for 400+ tokens) - they say mildly - are bad. There is no need to limit managers in training players with 3 *. The system of training players - the best among football managers - is the highlight of the game - and with such restrictions it will simply be destroyed.
it is enough to limit the negotiations on the time and / or number of sales to the upper and lower levels. there is a downside - when a player from the upper level is sold to the lower level - the player is bought at the upper level, for example, 59% and is sold two levels lower and automatically becomes 99%, and this is all for 5-10 tokens without any training costs. The main problem is not that players are transferred between levels, but that managers have the opportunity to lower the rating of teams before various draws - for example, on the last day of the season before the draw of the League Cup and on Thursday before the draw of associations (though for associations this is actually only for first lot in the season). As a result, at the entrance to the season / tournament of associations the team has, for example, 4 * and after a few hours - 5-6 * in the end, such tricky managers have a clear advantage. When I say that nothing will change if you "remove the mutants" - I mean it - there will always be cunning managers who will find a way to cheat the draws and unreasonably gain an advantage.