This seems to be a major regression on the iNat website.
If you go to any observation page (like this one) and follow a link to the profile of any user who ID’ed or commented on the observation, the link gives a 404. For example: https://www.inaturalist.org/people/radrat doesn’t seem to resolve to my user profile.
Just noticed this myself. Even my own profile won’t load, except up in the right corner badge where I am identified by a number rather than a user name.
Oooh! I haven’t seen the fail whale yet! Good thing we have a staff with a sense of humor. This lightens the mood and probably prevents a lot of grumpy answers.