Quote "Mobile Downloads.irdata file located on my Mac SSD.". That is a data file and normally resides in the Lightroom subfolder that contains your Catalog file. The extension .irdata that you quote is LRDATA ( as Lightroom Data) See the screen capture.
How did it now appear in your pictures folder as a Folder in your 2nd screen capture?
Regards, Denis: System iMac mid-2015, 5K 27”, Ram 24GB, HDD 3TB, macOS 11.1, LrC 10.1 (>10.0), Lr 4.1, Ps 22.1, Pr 14.8.0; Camera OM-D E-M1.