My brother owned several pairs of Fjällräven Karl trousers in different colours. They last approximately 18 month of continuous use, but get the first holes already after a year. My cheap Primark jeans last usually longer.
The fabric is too weak and the used thread is a bad joke. They are made to fall in pieces by the son of a man who tried to make the best possible outdoor trousers.
The stuff became unfortunately adventure fashion for those who don't really leave the SUV for more than a short dog walk.
Many years ago FR equipment was made in Sweden in superior qualities. But these days are gone.