I discovered a bug, there is a conscious copy of me following me around my railjack, vis image 1 and 2, he even has his own cat. I must say that this isn´t other player, I´m alone in the squad. I think that this bug is triggered when you extract from railjack mission when you are in operator form, if you have umbra equipped it´ll spawn a copy of your cat and umbra, however if you haven´t equipped umbra but some other warframe instead then it´ll just spawn a copy of your cat, vis image 3.
Here you have few screenshots as a proof, and sometimes when you enter your railjack it can spawn unconscious copy of you, vis Image 4.
Added: Soo I discovered that when the copy is in the ship with you when you start mission, it will go with you, it was helping me with my mission, both of them cloned umbra and kavat were fully functioning, umbra was killing and kavat was giving buffs.One player told me that he can see them too. vis image 5 and 6
Image 1: https://imgur.com/a/x6SYdum
Image 2: https://imgur.com/a/in6Bw8R
Image 3: https://imgur.com/a/vN74mXH
Image 4: https://imgur.com/a/Zj94wCQ
Image 5: https://imgur.com/a/5GFUZBu
Image 6: https://imgur.com/a/bhAvirK
EDIT2: added video
EDIT3: added more information