Hi,
I do not feel the same, but maybe it's depend of your expectations! Is it something that you notice especially on your video results? Or when you check other Mavic Mini video on youtube ( even at 1080 hd max) you feel the same? Do you compare with a 4k video result of a high end camera?
You can share a sample to check your video.
I've red somewhere on a forum that someone complained about video Quality, but in fact he was only using the draft video automaticaly available on the phone, but never take the real video that have to be downloaded from aircraft to phone, or copied from the SD. I'm not saying it is your case, but do you check the video from the aircraft SD card? And how is the performance of your SD card on aircraft (i thing that if SD card is not fast enought it can downgrade the video) ? did you use 2.7K 25fps or 30 fps setings for video?
Are you using "C" cinematique mode ?
Hope it help!