Hot take, but Betterman (1999). I was so pumped for it at the start, the designs and vibe were great. However, as it progressed and its thematic angles solidified, it became more clear that it was not going to be a good time, and I often regretted starting. The crossover novel fixed that a bit tho.
Mandalorin immediately comes to mind. The finale of season two where our hereoes stand around watching a CG Luke Skywalker do all the cool shit retroactively killed all good will I had for the show.