Mix rubbing alcohol and water in a sprayer and spray your shoes 1-3 times. Let them dry overnight. In the morning, sprinkle some baking soda in your shoes and discard until it's been 24h since lasting wearing. OR spray this in your shoes rather than using baking soda.

The second option is to swap rubbing alcohol with white vinegar. If your shoes still smell even after spraying them and letting them dry, then they're infected with bacteria/fungus and you'll need to buy new ones. Also, make sure your shoes are breathable. Plastic shoes tend to trap bacteria, like Allbirds.

Use this foot powder to fight against moisture. Put it in your socks along with baby powder. Use it on your feet. Put it in your shoes.

This works for me. And may not work for you.