Oddest is that it seems to be evenly not sealed along the whole length.
Usually over time, the end nearest the hinge will compress more than the open face, causing the seal to weaken farthest from the hinge as it gets used to being wedge-shaped over time.
The quick fix for that is to rotate the seal 180° [like a picture frame upside down] & refit. This is usually very easy to do, it will just clip in. Remove the plastic door insert first. That will give you another decade or so.
For it to be so far out for its entire length, though, makes me think the top hinge is offset too far outwards; either there's some adjustment in the structure which needs tightening back up, or the hinge is worn & needs replacing.
A late thought - perhaps it's meant to meet seal to metal, not half & half on the plastic. That could mean the bottom hinge has an adjuster for height, which has moved over time. Last time I had to re-jig mine, I discovered the lower hinge had actually slightly bent downwards over the years, but there was a double nut-lock which could be used to adjust the overall height.
You could try just lifting the door to see if there's any play in it & also if it will lift far enough to match seal>metal without the insert hitting the edge.
Another late thought - I wonder if the fridge insert, rather than the door insert, has moved forwards, holding the seal off the metal part a little, or even if the two inserts are hitting each other as the door closes.
Trying to see that happen will be like trying to spot the light go off… maybe something squishy, easily transferable on one edge, close, open, see if it's transferred to the other insert at all. All I can think of is lipstick, though I'm not sure how popular you'd be a) ruining the tube & b) getting pink everywhere inside the fridge ;) Maybe Vaseline instead.
