- [Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/14.1.2 Safari/605.1.15]
- MacOS BigSur 11.5.2.
UPD1: Now I have completed 9 more exercises and it did it again!
UPD2: Now also my Responsive Web progress got deleted!
UPD3: I have investigated the issue and it seems like the problem is with the Safari browser (at leat in my case). I tested the issue on Windows and it was not present. I also tested the issue on MacOS with Opera GX browser and it was also not present. While I have located the issue, I still have no clue on how to fix it.