Why Alonso was given a time penalty by the stewards for his role in the crash

"The Stewards heard from the driver of Car 63 (George Russell), the driver of Car 1​​ 4 (Fernando Alonso), team representatives and reviewed positioning/marshalling system data, video, telemetry, team radio, in-car video evidence and telemetry supplied by both teams.," the FIA document reads.

Why Alonso went slower through the corner

Both drivers spoke to the stewards. Alonso gave the following explanation: "Alonso explained to the stewards that he intended to approach turn 6 differently, lifting earlier, and with less speed into the corner, to get a better exit."

Russell saw it differently: "Russell explained to the stewards that from his perspective, Alonso’s manoeuvre was erratic, took him by surprise and caused him to close distance unusually fast, and with the resulting lower downforce at the apex of the corner, he lost control and crashed at the exit of the corner. There was no contact between the cars."

The stewards saw from the telemetry that Alonso braked more than 100 metres earlier than he had done up to that point in the race. The Spaniard also braked very lightly at a point where he had not done so earlier in the race. However, braking was not the biggest factor for slowing down, that was the fact that Alonso downshifted earlier. Again, he had not done this anywhere earlier in the race. Alonso explained that his plan was to slow down earlier, but that he got it a bit wrong and had to take extra steps to get back up to speed.

Why Alonso got a 20-second penalty

However, the stewards believe that in this case, Alonso was driving slower than necessary, potentially endangering another driver. In doing so, the stewards are referring to Article 33.4 of the sporting regulations. The stewards did not consider the consequences of Alonso's action in the decision.

"Should Alonso have the right to try a different approach to the corner? – yes. Should Alonso be responsible for dirty air, that ultimately caused the incident? – no. However, did he choose to do something, with whatever intent, that was extraordinary, ie lifting, braking, downshifting and all the other elements of the manoeuvre over 100m earlier than previously, and much greater than was needed to simply slow earlier for the corner? - yes by his own account of the incident he did, and in the opinion of the stewards by doing these things, he drove in a manner that was at very least “potentially dangerous” given the very high speed nature of that point of the track."

"This season, the FIA Formula 1 penalty guidelines, including for this breach have been reset and increased to a baseline of a 10s penalty. In addition, when there is some aggravating circumstance, we consider a Drive Through Penalty. In this case we consider that Alonso affirmatively choosing to perform an unusual manoeuvre at this point to be an aggravating circumstance, as opposed to a simple mistake. The stewards therefore order a drive through penalty, which will be converted to 20 seconds added to Car 14’s elapsed time, along with three penalty points."