If I may: Injuries and red cards.
I see many frustrated with that saying they do all they have to to minimize them yet they have many injured players and long term injuries. I don't mean to doubt them, but thing is, several of youtubers I follow I've seen complaining of that (past versions more than this) and there's something to say about that. Perhaps, those posters do the same.
They say "no high intensity training". Not seeing their training schedules (none who I follow does, I think one would but I don't follow yet) I have nothing more to say.
The first place I have something to say is when they say "I don't tackle hard". Ok, some showed his tactics and indeed, neither team nor players have tackling hard checked. But then you see them going into the match. Soon they get to the OI instruction, they click the apply assistant's advice and move on. And there, his advisor has set players, often a lot, sometimes every outfield player and the goalkeeper's granny to tackling hard. So that part that they don't instruct tackling hard? False. They do the moment they are taking the advice in OI to tackle hard enemies. Players will use their team and tactical instructions; but when facing the opposition players, if it has an OI set, they will follow that over what the tactic tells them, so if you set tackling hard to a rival, all players will tackle hard when meeting that rival. If you take advice to tackle hard a lof of players it won't be different than giving your players the tackling hard instruction and hence raising the risk of injury. And of red cards.
The second is only related to injury. And this is what I've observed some of those complaining of the gravity of injuries: they get a player with a non red cross who's dropped more than 10% condition and... they do nothing. They keep playing him. I've ever seen them keep on the field someone whose condition dropped from 89% to 49%. Sometimes they eventually sub them when in mid of second half, but I've seen players injured like that in min 5 that have played the rest of the match. How is that doing everything to minimize injuries? If you get one such knock in a match, the longer he plays the more chances the injury will be worse. As a rule of thumb: if condition drops more than 10% the player must be subbed immediately or the injury will almost sure be serious, immediate sub may leave it at something short. If the condition drops less than 10% then you have a good chance that keeping him playing won't make it too bad. I think the longer injury I've had from a player dropping less than 10% and kept on the field was 4 weeks but most don't go beyond 2 weeks; and by subbing immediately I've had knocks that dropped up to 35% last just 5 days. That's how I rarely have injury crises and more or less an average of one 2+ month injuries per season and some seasons with none like that. Keep your eyes open for injuries that don't force players out, watch how much condition dropped, if it did more than 10% or you're not sure: sub him immediately unless you don't mind losing that player for months. If condition dropped less than 10% then you may consider not subbing; but be careful, there's the odd injury that drops less than 10% and still lasts beyond two weeks.