Interviewed with a company recently and they gave me a take home assessment after my initial round with the hiring manager. This being my first take home assessment ever, I excitedly sat down to solve it. I took about a couple of days (had other things to do) and sent it over. I even wrote some basic tests despite the instructions saying that they were okay to skip (wanted to impress my interviewers).

Got rejected a week after submission with no explanation. It was a really good problem and I had fun solving it and it satisfied all the requirements correctly. When, disappointed, I asked them for feedback, the recruiter simply said that they "felt that it fell under their expected level" and that "The team has a very high bar set for this role and have made it a point to make sure people who join the team can contribute immediately which unfortunately means tough decisions like this have to be made". They didn't share any specific feedback on my code despite my following up for more specifics. Really pissed me off.