@Larymir@chaos.social Assuming you're in Germany, Lidl has an online shop there too I believe, and I've had pretty good experiences with their cotton sheets overall (and the online shop usually has a pretty big back catalog of options and colors, unlike the stores).
The absolute cheapest ones are the half-transparent ones and I would avoid those, but the slightly fancier ones (eg. the 'satin feel' type ones) are usually of much higher quality, and most of them are still 100% cotton.
Like this one from the NL shop for example, I would expect that to be a nice one: https://www.lidl.nl/p/livarno-home-satijnen-hoeslaken-180-200-x-200-cm/p100388390 (and I *think* it is in fact the same one as my favourite sheets)