My un-favourite thing is actually all the instances of Rudeus pervying over his own mother, but yeah, I think this is as bad as it ever gets. Also, I feel that this part of Mushoku Tensei is why so many isekais after it made the protagonists either reincarnate as adults or awaken their memories of previous life at grade-schooler age. You can easily imagine how traumatic the experience of a fully self-aware toddler would actually be unless they're some kind of extreme pervert.
Yeah, I read a few chapters at the start. I think the last chapter I read was from the maid's perspective, where she said how uncomfortable she was around the MC, while no one but her realized that there was something wrong with him. And yeah, that was pretty disturbing.