Ravindra Jadeja has bowled 52 front-foot no-balls in Test cricket since December 2020. Of the 18 overall no-balls he had bowled before that, four had bounced more than once, and seven were detected by the third umpire because they had either resulted in dismissals or were reviewed under DRS. We don't have records that confirm all of the remaining seven were indeed front-foot no-balls. Be that as it may, you get the gist: Jadeja has been bowling an extraordinarily high number of no-balls since late 2020.
In a way, this increase in no-balls has nothing to do with Jadeja. In mid-2020, the ICC handed over calling of all foot-fault no-balls to the third umpire. Before that turning point in cricket, the third umpires used to check for no-balls only if the ball had resulted in a dismissal or if a non-dismissal had been reviewed by the fielding side.
Now Jadeja is the perfect illustration for why you need a third umpire, for why it is so difficult to call no-balls on the field. He pushes the line anyway, but to add to that, he doesn't land flat. His front foot goes well over the line in the air, then he drags it back while still in the air, and the toe makes the landing first. The umpire has to quickly draw an imaginary straight line from his heel to the ground and calculate in their head if it falls on the popping crease or just behind.
That most of Jadeja's no-balls are only caught on replay means he hasn't started overstepping in 2020. Just that, he has started getting called for overstepping in 2020. Just imagine how many no-balls were missed before the third umpires started to check every ball for a foot fault. Not just from Jadeja, but especially Jadeja, because his landing is so difficult to work out.
In another way, the increase in no-balls has everything to do with Jadeja. Since the third umpires took over calling all foot-fault no-balls, starting with the Test series between England and West Indies in July 2020, Kagiso Rabada and Ben Stokes have sent down the most foot-fault no-balls: 77. They are fast bowlers, and their increase from before third-umpires is not huge - 50s to 77. No spinner, however, comes even close to Jadeja's 52 no-balls, and he has gone from seven foot-fault no-balls to 52. At No. 5, he is the only spinner among the top 14 bowlers of no-balls since the third umpire started checking every ball.
Jadeja is one of the all-time great spinners and allrounders. He is such a gifted athlete that everything on the cricket field seems to come naturally to him. He is like a well-oiled machine on the road: smooth and seemingly effortless. This is not to say he doesn't work hard, but he does give the impression that he does things the way he knows, and most of the times it just turns out to be too good for most other cricketers.
With these no-balls, though, Jadeja needs to put in the extra effort. And it is not a big effort. Most of these are extremely marginal no-balls, and avoiding them requires only a small adjustment. A Test cricketer shouldn't take so long to respond to a rule change.
Known for his glib, funny one-liners on the field, India's Test captain Rohit Sharma shouted during the ongoing Test series: "This Jadeja doesn't bowl no-balls in the IPL, man. Jaddu, just imagine it's T20."
In T20s, with the threat of the free hit around, Jadeja has overstepped just twice since 2020. In ODIs, he has done so only six times. The same should be easy to apply in Tests. In this series alone, Jadeja has bowled 11 no-balls, nearly twice what anybody else has. Luckily none of those has impacted his 17 wicket-taking balls, but it shouldn't take a no-ball to cost him a wicket to make that adjustment.