this explains it better than I could:
https://www.planetf1.com/news/fernando-alonso-brake-test-accusations-unfair
"... The fact is that Russell went off and crashed, based on what the car in front of him was doing – this having been verified as Alonso lifting off early, rather than being a brake test in the true sense of those words.
It meant that Alonso’s driving could be viewed as “erratic” or in a manner “potentially dangerous”, which is covered under Article 33.4 of the Sporting Regulations.
This meant that, regardless of Russell’s crash, the stewards would have had the grounds to examine Alonso’s driving if they’d felt like it. The stewards also said that there was insufficient information to be able to say whether or not Alonso’s driving was designed to cause Russell problems or whether he was simply trying to get a better exit.
The issue this wording raises is whether or not it should be relevant. After all, isn’t the art of defensive driving down to causing your rival “problems” and ensuring they can’t do what they want to do?
Alonso didn’t slam on the brakes, didn’t change direction without warning, and performed an action – however scruffily in execution – that, unlikely intentionally, caused Russell a problem that he couldn’t overcome.
The stewards admitted Alonso had the right to try a different approach, and was not responsible for the dirty air that destabilised Russell. But it was in the nature of his “erratic” driving that allowed the stewards the grounds to punish Alonso and, with Alonso’s account of his approach to Turn 6 confirming an unusual approach, it meant the stewards could rule that he had driven in an erratic or “potentially dangerous” manner – thus the penalty.
Essentially, Alonso has been caught out by a rule that is open to interpretation and is there to catch egregious examples of misbehaviour from drivers. The Spaniard himself took to social media after being given the penalty that dropped him to eighth place (and three penalty points applied to his super licence) and explained the situation from his perspective.
“A bit surprised by a penalty at the end of the race regarding how we should approach the corners or how we should drive the race cars,” he said.
“At no point do we want to do anything wrong at these speeds. I believe that without gravel on that corner, on any other corner in the world, we will never be even investigated.
“In F1, with over 20 years of experience, with epic duels like Imola 2005/2006/ Brazil 2023, changing racing lines, sacrificing entry speed to have good exits from corners is part of the art of motorsport.
“We never drive at 100 percent every race lap and every corner – we save fuel, tyres, brakes, so being responsible for not making every lap the same is a bit surprising.”
It’s notable that Alonso’s incident warranted a harsher response from the F1 stewards than what the F3 stewards applied to Nikola Tsolov earlier in the weekend.
The F3 racer was aggrieved by being impeded by Ireland’s Alex Dunne during practice, and promptly clattered into his rival by deliberately steering towards him and sending Dunne into the wall – the MP Motorsport car picking up extensive damage in the crash.
Tsolov was given a three-place grid drop but the stewards, astonishingly, didn’t treat the incident within the context of it being a deliberate act and, even more astonishingly, pointed to Dunne as being the instigator of Tsolov choosing to use his car as a weapon.
In contrast, Alonso chose to use a defensive tactic (albeit clumsily) by simply slowing down approaching a corner in order to block his rival, and found the book being thrown at him when his rival was caught out by it (and admitted to being caught out by it). Unlike Tsolov, Alonso can hardly be said to have used his car as a weapon, merely a hindrance.
Had the telemetry revealed that Alonso hitting the brakes had been the primary reason for his car slowing down, or if he had been only a tenth or two ahead of Russell, it could be said Alonso deserved his penalty. It would change the complexion of the offence into something far more sinister.
But simply easing off the throttle and then accelerating again, while half a second clear of his rival, shows that Alonso was merely trying to use the dirty air effect to stymie Russell’s momentum – a typical racing tactic that didn’t warrant the penalty he received."
