What would make a pot of chili tastes like vinegar?

Too much vinegar: This is the most obvious one. If you add too much vinegar to your chili, it will obviously taste like vinegar. Be sure to measure the amount of vinegar you add carefully, and taste your chili as you go to make sure you don't overdo it.

Tomatoes: Tomatoes are naturally acidic, so if you use too many of them in your chili, it can also start to taste like vinegar. Try using a combination of tomatoes and other vegetables, such as beans, corn, and peppers.

Other acidic ingredients: Other acidic ingredients that could potentially make your chili taste like vinegar include salsa, hot sauce, and Worcestershire sauce. Be careful not to add too much of any of these ingredients, or your chili could end up tasting more like vinegar than anything else.

Cooking time: If you cook your chili for too long, the flavors can start to break down and the chili can start to taste bitter or vinegary. Be sure to follow the recipe carefully and cook the chili for the recommended amount of time.