Loki( part 7): 2012 Loki created new alternative timeline.
After Loki's death , Avengers fought against Thanos but Thanos successfully snapped and half of the living being turned to dust. Then somehow remaining avengers plans to restore that half population but stone were already gone as Thanos used some stones to destroy stones later . So Avengers plans to bring the stones from previous timeline using Time travel .
The team of Iron Man and captain America travelled to 2012 timeline in London after Loki's attack. After this attack ,Loki and Thor were supposed to go back to Asgard. With the help of Iron Man and Ant-Man they almost had got Tesseract but the way Ironman was walking led to conflicting path with 2012 stair walking Hulk and Tesseract fell down infornt of Loki. Loki who was prisoned with hands took that Tesseract and entered into new places.
Since according to his previous timeline he was supposed to get back to Asagrd but he escaped that events and created new timeline . For creating this new timeline ,he got captured by Time Variance Authoi for Short TVA.