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” monitor, macOS10.15.7: LrC 10, Lr 4, Ps 22.0,; Camera OM-D E-M1.