Most managers after changing club change preferred formation to 4–2–3–1

[RealSmokePL]

Quite annoying seeing this happen so often, leaves little variety after a while with most managers playing the 4–2–3–1 no matter their starting preferred formations or the clubs preferred formations, I'm not sure if this is just the case in Poland as that's where I always play and rarely (aka never) outside of it.

[RealSmokePL]

Also in a few cases the manager doesn't even have to change clubs to change formation, even if they were successful with their previous formation(s).

Sometimes I see this making the manager perform worse by a lot and a sudden change to the 4–2–3–1 is I believe the cause so I don't understand, + why is it always the 4–2–3–1

[andu1]

The issue has been brought up for FM 20, and most recent on FM 21 bugs forum. The best guess is that the game interprets this formation as the META formation and that's why the AI is tending to use it more than the others.