That’s very common with the yellow paint, the red ones suffer from pealing lacquer/clear coat. My red one has this only on the door handles and front bumper. I think it hasn’t spread further because I haven’t washed it for years!
If you’re looking for a diesel then don’t discount the 110 and 130 models. There aren’t many of the 130pd around but they tend to be cheaper and almost as fast as the 150pd without some of the extra problems. The 110 has the very old AHF 1.9 which is very reliable and can go well over 200,000 miles. I’ve had my 110 SE for 11 years and had very little problems, plus it has the same suspension and interior as the 1.9tdi cupra. It isn’t as fast but most of time its quick enough for me and you can remap them to around 140bhp for under £100.
Also if you don’t need a hatchback the Toledo is the same car with a boot and normally has better equipment than the similar Leon model.