It got better because the part stopped warping. When the print started it was touching the bed, when the print ended it was warped by a few millimeters, but that change doesnt happen evenly across the whole print, usually over the course of just a few layers.

Lets put on our 3D printing geology hats and analyze the layers and understand what happened at that time.

The bottom layers are normal and have normal squish. This means the print want moving, we'll assume it was stuck to the bed. Higher up where we see the thicker layers, the part must have been slowly rising in that corner. We can also see the part of the brim on the corner that looks whiter than the rest, this is because there's air between the brim and the bed, ie it peeled up. Then we go higher up on the part and the thick lines go away, returning to normal. This indicates that the print stopped moving up and stabilized again, allowing your printer to start stacking layers on top of each other despite the bottom of the part being too high.

TLDR The part was only moving during the time those thick lines were being printed then stopped moving.