Bottas moved to the right while Russell was passing which forced Russell into the wet.
It was only a small amount, and it was only a single move, but in the rain, stuff like this can happen. Totto is pissed because the car is apparently totaled and not repairable. They do have a money cap, so this cuts into their upgrades.
IMHO, it's Bottas fault and this is why I have that opinion.
Even with DRS, why was Bottas driving slow enough for a Williams car to be able to pass him? That just should not happen. Bottas was having a shit race and saw a Williams was about to pass him and basically pulled a mini road rage feint. When Russell corrected to avoid him, the car spun due to the rear wheels hitting a wet spot.