That's because people were going on with high expectations, right? I haven't seen it (yet?) but Morbius and Madame Web both got C+ and I'd be surprised if it's actually worse than those. Although I'd be more interested if it really is that much of a trainwreck tbh, I liked the first movie well enough but didn't think it needed a sequel, I was just going to pirate it next time I was bored at work.
I think one factor is that people are running out of patience, way too many of these franchise films and shows from recent memory have been considered terrible by a majority of viewers.
If MoistCritical's review is to be believed (that's the only one I've seen so far) it apparently doesn't even have much of a plot, which would be enough to make it worse than Morbius.