Ajax often set up with a 2-1 build-up structure with the DM dropping deep to provide a close passing option to the two centre backs, with both full-backs moving higher up the pitch, allowing both wingers to tuck inside into the half-spaces.
The left-back will drops to collect the ball, which allows the left-sided central midfielder to move higher to create a 4-3-3, whilst enabling all three midfielders to occupy the three vertical lanes and creating a 3-1 shape in at the back with the width being held by the LW. Strengths of the 4-2-3-1/4-3-3 hybrid
Creates natural passing triangles.
Get good balance in Central Midfield with 3 CMs (allows one to attack).
Natural Anchorman protecting back four (allows FBs to advance).
Can move into 4-1-4-1 during lengthy spells without the ball.
Left CM can drop and add protection to the back four.
Can create double-pivot to offer good passing angles when building.
Wingers can invert to create overloads in half-space with FBs supplying the width.
The CF is heavily supported by attacking midfielders.
Check out https://breakingthelines.com/tactical-analysis/erik-ten-hags-ajax-a-4-3-3-4-2-3-1-hybrid-2/ for Ajax tactical analysis written by https://twitter.com/MrArhumSiddiqui