Project Window

It got disconnected and I can’t figure out how to reattach it to the bottom of the project.

drag it around (from title), it should snap other window edges.
or reset or choose included layouts, menu: Window / Layouts / …

sorry just still not sure.
6937567--815152--upload_2021-3-15_15-4-7.jpg

it should snap there,
6937747--815170--snap.gif

Worst case, just go to Window → Layout.

thank you