i am a fireboard user and we have a lid detection setting where you can disable the fan when there is a sudden drop in temp (lid open)
i'm not sure if you can enable something like this in the billows app. if not, the fan may be overcompensating when you opened the lid as seen in the green spike. also what is your max fan speed set to? if max speed, it's going to be trouble..
also, are you using the yellow billows damper?