I was going to say washing detergent, drying sheets…hmmm…and it does look like some sort of lotion residue as my wife causes this once and awhile with even hand cream. Not saying it’s this but it’s quite similar to some sort of external layer.
Suggest you just place a towel on your seat or a seat cover for a week instead of actual tape if you don’t want to risk damaging the seat material with tape adhesive sticking.to it afterwards.
I’d recommend a brand new towel, not something washed at home. Just to eliminate any possibility of a home based chemical.
Alternatively you can go the way of ordering a seat cover and enjoy a different colour at the same time
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