I don't think that any of them are for 4 post lifts, I fitted them to my wife's 2002 VW Polo just for my convenience when lifting it on trolley jacks and then supporting it on the sills using U section adaptors, I also fitted another set (could not get the originals out of the old car quickly enough) to her next new car a 2015 VW Polo. I've never ever noticed any issues with corrosions relating to fitting these Audi MK1 TT jacking point protectors. On the Polo, all these points were plugged up from factory - so no drainage issue when fitting these protectors.
Having watched that 2015 Polo up on a 4 post lift in the VW
dealership, they did not use anything other than the sills to lift it - which makes sense as it is easier/safer for the operator to see where to locate the ends of the lifter when they are placed as far out as possible.
I've lifted up my older daughter's 2019 Leon
Cupra and used suitable adaptors - hand made, that do not allow the vertical folded-welded seam
lower end to be in contact with the adaptors - all the weight is carried by either the inner flattish surface or the outer flattish surface - I've forgotten now which it was for that car. One thing that is annoying for me is, I have a 2011 Audi S4, a 2015 VW Polo 1.2TSI 110PS and a 2019 SEAT Leon
Cupra that I tend to look after, ie need to lift up, and the profile of the fold-welded vertical seam and the surrounding flattish areas, are very different on each of these cars, which meant that I have needed to make up a new set of adaptors for each car - which for a single car building group, is a bit silly.
I'd be willing to bet that all of these 3 cars get lifted, at their own marque
dealership, by applying the lifter on the
lower edge of the welded-folded seams, okay with a hard bit of rubber as a padding, and that is that.
Even lifting with my style of adaptors, pressure/load is placed on the undercoverings and yes they creak etc a bit, but so far no cracking or bits breaking off.
As I bought myself a full set of Jackpoint jack stands (seriously expensive but very effective so far), I can't see myself suggesting that my older daughter fits Audi TT MK1 jacking point adaptors to her Leon
Cupra - and I have to question my own decision to bother to fit them to wife's 2015 Polo, but if I'm being extremely lazy and ignore all lifting precautions, using these Audi TT pads and 2 trolley jacks, makes swopping Winter<>Summer wheels/tyres so quick and easy - okay when swopping them over in late Spring/early Summer, I'd probably every or every other year, service all the brakes - so I revert to using 4 Jackpoint jacking stands to make life safer.