I once had a similar discussion with an insurer a few years back about removing alloys and fitting steels on my battered old 20 year old Hilux, they wanted to charge me more for the downgrade as it was now modified!
At the time I had two sets of wheels, one with road tyres on alloys and one with muds on steel, I was just about to get a new set of road tyres and it was cheaper to get them on a new set of steels than have the existing ones removed and new fitted, so that then led into a discussion about if I should inform them everytime I swapped wheels, (once or twice a month at the time for events), woman on phone said yes I had to tell them and it would be an admin fee each time!
I asked them if they also considered all the bits of exterior trim and bodywork that had been removed by a combination of trees, rocks and other immovable objects as modifications, the woman on the phone said “yes, if it’s different to factory spec then it counts as modified”
Suffice it to say I moved to a more sensible and accomodating insurer.