But don't buy the name brand. Use Citric Acid (the stuff for canning tomatoes). Run an empty hot cycle with 2 tablespoons of citric acid. It dissolves detergent scum better than bleach.
If you just snake the standpipe, you are pushing the clog deeper into the trap. You need to pull the auger back toward you to hook the sludge and yank it out. You will eventually get this clog again. Sludge is inevitable. But you can turn a "once a year emergency" into a "once every 5 years maintenance." washing machine drain clog
The sludge is winning because you wash your gym clothes, your muddy towels, and your dog beds in cold water with too much soap. Cold water doesn't melt grease. Too much soap creates sludge. But don't buy the name brand
Your washing machine is incredibly strong. It pumps water out with force. If the water isn't leaving, it usually isn't because the pump quit; it’s because the water has nowhere to go. It dissolves detergent scum better than bleach