A former lotus engineer talks about porpoising. Very insightful and a short video if you guys want to watch.
The interesting thing is that he says porpoising is a damping issue as well, and the cars with the most porpoising have the highest down force generation.
This is intriguing because on F1 technical they are speculating Mercedes got the rear damping wrong in particular. Because they are trying to get the car to squat like last year to increase down force generation at high speed but they got the linkage and pivot positions all wrong causing the porpoising to be in the rear, because the front doesn't bounce at all unlike other cars that porpoise like Ferrari where all 4 wheels bounce. F1 technical also suspected the w13 to produce insane amounts of downforce on the front floor mouth due to the way it's shaped, and in other portions of the floor which contributes to porpoising when those pressure zones move about. But the high downforce notion kind of makes sense because the w13 is still able to be 3rd fastest despite running a compromised ride height and suffering from the major bouncing issues.