It is, was hoping for a full 3 car garage, but this turned out to be our favorite home and 2.5 should work (~540sq ft). Haven’t ever had a full garage to myself before, so I’m excited to get it all set up
Before you do any more sanding, make sure that is not veneer rather than solid wood. It doesn't take much to sand through thin veneer. It could be just a natural dark place in the wood. However, if you think it could be some kind of stain, you might try a wood bleach. Oxalic acid is a one part bleach that is inexpensive and easy to use. If that does nothing, you might try a two part bleach (sometimes referred to as A-B bleach). If it is veneer and the bleach doesn't work, you will need to use a toner (colored finish) to blend it in. Or, just leave it alone.
What did it look like before you started stripping it?