Which 737 Max8/9 seats have the ultra-low under seat clearance?

I have noticed that there are some seats on the 737 Max8/9 on United that have extremely small clearance under seats due to both IFE and the life preserver. A helpful redditor measured this at about 5 inches a couple of months ago ([Reddit - https://preview.redd.it/b737-max8-9-backpack-no-longer-fits-under-seat-v0-h6ci1x5llpjf1.jpeg?width=3024&auto=webp&s=4fa765424e15220531839c7d79adb047d6358e40](https://www.reddit.com/media?url=https%3A%2F%2Fpreview.redd.it%2Fb737-max8-9-backpack-no-longer-fits-under-seat-v0-h6ci1x5llpjf1.jpeg%3Fwidth%3D3024%26auto%3Dwebp%26s%3D4fa765424e15220531839c7d79adb047d6358e40)). This is substantially smaller than the personal item guidance on the United website, but that's beside the point of this post.

My experience is that this isn't every Max seat. I experienced this yesterday on a Max8 in an economy plus middle exit row seat. I do not commonly fly in the middle seats, so I don't know whether this is common in all middle seats, unique to the exit row, or something else? On Friday of last week I sat in a regular economy seat on the aisle on a Max8 and it was clearly not this short.

Does anyone have any thoughts on which seats have this situation? It's not a huge deal but would influence which seats I pick or which bags I bring.