hello @Zachary Whyte, i want to thank you for addressing my issue and I'm happy you will further investigate my issue. While I mostly agree I would like to comment on some things that you mentioned.
I mostly substitute players only when their condition gets to poor because I don't want to risk an injury or their level of performance is not at the required level, IRL a player, especially because he is star player, understands that at some point of the match he is being subbed in order the get rested for future matches and/or not risk and injury if the match is already decided. I can understand a star player being upset for being subbed when his team is losing/ drawing for not being able to demonstrate his worth but i assure you this is not the case.
In the screenshot i provided you can see that the Actual Playing Time for musiala is the one of a Star Player so him being concerned about not having the playing time of a star player doesn't really make sense. Both Musiala and Abraham are getting the agreed playing time and yet they are concerned
abraham and musiala are both my best players and are in top of the squad appearances. they play more than everyone else in the team and they are the ones concerned
in the end all i'm saying is that their reaction is not justified at all is the more curious since the game says their are getting their agreed playing time
i will wait your further investigation into the issue.
thank you again!