Replying through my kbin since i can't reply to kbin from lemmy.world right now for a reason:
It's not actually my reddit api pull. As far as I understand the code, in a regular time intervall the newest post and comment are pulled to obtain the per minute data.
Not sure if that info is directly obtained from the reddit api, or if they use a comment/post ID to calculate the difference between each sampling point. Am not that good at coding myself.
But yeah i think that reddit could manipulate that data without issues.
There are some paying traffic monitoring sites that apparently showed a dip of 20% too (Reported here). They also report that the average time spent and session counts went down by 14% and 8%. Since this data is not obtained from reddit directly I think it might be a bit more representative
I did have trouble today replying between kbin and lemmy.world and vice versa. Not sure if it also applies to other instances