This is the actual account claimed by JUMBOKILLER2001. It has a skin, too:
The following are demo accounts (according to MC-51758) all sharing the username "JUMBOKILLER2001", but the response doesn't include anything that indicades they are demo accounts:
This is a problem because it is not possible to determine which one is the actual account (without additional API calls) and @KrisJelbring said that the intended behavior is to not return demo accounts.
Linked issues
Comments 6
Just to clarify. What I meant to say in the earlier comment was that the intended behavior of the profile lookup API was to not include demo profiles. They may still occur in other parts of the system.
Still not fixed. Whilst this doesn't seem like a huge issue, it actually sort of is. This breaks a lot of sites that try to give accurate information to the Minecraft community. Demo accounts shouldn't be returned by the Mojang API (uuid/names) but it would be acceptable if they are by session server but have the field 'demo' in them (they do not currently).
"Lol" is also a demo but is returned as legacy account while this is a demo account as recently the name got claimed (https://sessionserver.mojang.com/session/minecraft/profile/3c08435d4b17484ba39c79eb14bcafce - https://api.mojang.com/user/profiles/3c08435d4b17484ba39c79eb14bcafce/names)
Edited the UUIDs + links. I somehow cut off the first character of each UUID, sorry.