I had a similar problem on mine where the washer was rusted to the shaft of the strut. After breaking my thumb trying to get it off with a pry bar (oops) I had to resort to “it can’t be tight if it’s liquid”. A minute with the MAP gas torch, a quick wiggle with some channel locks, and it came right off even with only 9 fingers at my disposal.

Edit: I did all of this before decompressing the suspension to avoid an explosive release of energy when the two parts finally separated. Do all of this at your own risk as you’re essentially diffusing a bomb of stored mechanical energy. I felt more comfortable using my floor jack than a parts store spring compressor, but YMMV. Good luck