I don't think it's something any of us will be able to point you to, since we're looking at the same thing you are – it's just you look at that open space and see reward, and we look at it and think: what terrible programming. As for "each has a man he's tracking" and "one defender
even leaves" another player unmarked... wow: welcome to the modern football press, where everyone stays attached to a man and maybe one player might leave to go and do a half-hearted press.
This is just not how space is compressed in real life in most top-flight games across Europe. The back lines here are acres apart; the AI back line is broken needlessly when Mendy gets into space; teams in real life do not generally stick to man-marking principles; midfield congestion is actually a thing in real life too.
What's clearly worsened it here – something
@manmachine pointed out and I had failed to see at first – is the 2 red cards. Maybe that's why there's basically no defending and no midfield. (But for that reason also it just doesn't look to a lot of us as very rewarding to have found that space

)
The point is also that it's a more general problem in this game (not confined to your match), and that it was a massive problem in PES too. Some people lauded recent PES games as the epitome of realism, but it's this complete lack of care for real tactics, shapes, and patterns that sticks out like a sore thumb for the rest of us.
That's also why this point is petty and unfounded:
Not only is this criticism relevant to your clip, it's relevant to eFootball as a whole, and to PES going back years also. I'm sorry you don't think that there's anything "actually wrong" in how this game simulates defensive principles in football.
I'm not alone in pointing this out either, to others here also the problem is glaring: