I used sexual water based gel lube that expired may of 2021. i just noticed. is this bad? can i use expired lube?

The expiration date on these products is the last time the manufacturer assures the potency and effectiveness of the product. It doesn't go bad like a food item might, but it begins to break down some. It may not be as comforting as you would like, but you can use it until you replace it. (Soon would be good)

Using expired lube will not do you any harm. As Dr. Ferguson advised, replace the expired product at your earliest convenience. Practice safe sex : https://www.hopkinsmedicine.org/health/wellness-and-prevention/safer-sex-guidelines