A little background about me: I am an undergraduate engineering student (graduating in June 2022) currently doing my semester of bachelors. In my penultimate year, I did a research internship with an overseas university with a great professor. Although I learned a lot from that internship, I would be lying to say that I enjoyed my time. The work was pretty tedious and the tools were not at all helping me in any way. I grew frustrated. The task was large and often I ended up getting scolded by him. The expectations were high, weekly deliverables were massive and I was often left helpless without much resources both on the internet and text. Although I was able to complete my stipulated internship duration of 6 months under him, he asked to work informally under him, even remote, without an incentive as long as I could. I worked for a month more but then graciously asked my supervisor to relieve me of my duties as my home college session had started and I had to return to campus full-time.
Present: It's been almost 5 months now since I ended my internship and although I hated my internship work, I wrote an email to him thanking him for all the good learnings I had under his guidance and wished him a very happy new year. Today (after 10 days of wishing), he e-mailed me with the proposition to work under for the same role, the same task again. I would not want to work under him again (as I believe my interests vary from the internship and my struggles) but I don't want to hurt him as he is a very good and humble human and lots of students would love to grab the opportunity he's extending to me.
How should I decline the proposition of working under him, politely? We're about to have a team meeting online this week? Any suggestion is welcome as to how to deal with the situation as I am clueless about this.