1t-1T (teaspoon, Tablespoon) lemon/citrus juice and a literal two-finger tiny pinch of baking soda, without buying specialized chemical compound ingredients off of Amazon that may be lying about their contents.
Sodium citrate is already in citrus and the baking soda kills the acidity that may make the taste more harsh (another great trick is adding a pinch of baking soda to homemade tomato soup to kill the tomato acidity and blend it better with added milk/cream).
1T of white wine can do wonders for cheese sauce as well.