The Pixel 6 and Pixel 6 Pro have not been out long, but there are already complaints of first-party cases discolouring and deforming. Apparently, issues arise after a few months of use, despite their US$29.49 price tag.
https://www.notebookcheck.net/Complaints-about-official-Google-Pixel-6-and-Pixel-6-Pro-cases-mount-up.622834.0.html