Regarding 433 with midfield positioned more closer vs 4231, there is a huge shift towards 4231 in European football in the last 2-3 years.
4231 with two pivots is offering way more protection against counters and is more suitable for Flick's football with a high defensive line.
Also, AM is offering an extra presence around the box and is helping against problems of a classic 433 (Barca 2016-2022) where we had too much possession, too many sterile passes and not enough threat around the box.
For a majority of teams, 4231 is currently a better option both in defense and offense.
A good old 433 with tighter midfield can be used only by clubs like Psg who have a top class midfield, awesome fullbacks and attackers who can press.
In our team, we have Lewa who doesn't press so we need two pivots to protect the defense (and flanks) when our pressing gets beaten.
Further, if we want a tighter, more balanced midfield, then we'll lack the 4th guy in the box since Pedri, Frenkie, Casado aren't dangerous around the box.
Further, if we'll play with a tighter midfield, we'll need more attacking fullbacks to provide the width and attacking power.
The days of Barca's 433 formation are behind us, in tactical terms.
As said above, a majority of top teams have moved towards 4231.
Or towards 343 in possession with a fullback who turns into a pivot and then the team creates "a box midfield" consisted of 2 pivots and 2 AMs.
But, BOTH 4231 and "box midfield" formations have 2 pivots because that's the new norm in football, especially if you play an attacking football paired with high pressing.
If you play with only 1 pivot today paired with a high pressing, you'll end as Barca vs Liverpool, vs Bayern and similar.
Zero protection once when you lose the ball or when the opponent beats your press and they are free to do whatever they want in counters.