I agree with serbian u21 player rule, but the 4 non-EU players rule can make the game too complicated and, for some players, even unplayable. Hypothetically you enter the 2029/30 season with 9-10 non-EU players. Before you enter the EU, it’s easier and cheaper to build a squad around South American and African players, for example, because it’s hard to attract players from more significant leagues to Serbia. Game will not warn you about rule changes and you can play 4 in first 11 and have rest of them on bench. But you enter the 30/31 season with a similar squad, and you can have only 4 of them in the match squad. It makes sense to change rule to addopt to new circumstances but 4 players in match squad is too harsh.