it appears to be related to Annotations on this observation. if you collapse the annotation section so that you don’t see the details on observations, you’ll be able to scroll down on the observation page.
it looks like a user 1142264 made some agreeing / disagreeing votes on the original annotations, but that user no longer exists. so the page doesn’t know how to handle that situation… well, except that when you’re logged out, it seems to handle the situation by suggesting that iNaturalist made the agreeing / disagreeing votes:
i don’t know why there’s a difference in behavior when logged in vs logged out, but i think if the unknown user case is handled in the code more gracefully, things will be okay.