i assume lichess has time based puzzles so people can be failing the puzzles because they are trying to optimize how many puzzles they solve rather than making no mistakes. also, i suspect lichess puzzle ratings probably do not match with lichess chess ratings (sure, they probably correlate but i suspect there could easily be a +200 average difference or something like that between them) . i can solve puzzles consistently at least 1000 rating higher on chess.com than my chess.com rapid rating. also, if you know these puzzles are mate in 1 then they are much easier. i'm guessing you didn't know when you initially solved them but i think its much harder for other people to judge the difficulty of these puzzles if they know the solution is mate in 1.