ChatGPT Plus has a listed price of $20 per month, but the actual cost you pay...

https://atomic-wiki.win/index.php/ChatGPT_Plus_Deep_Research_Not_Working:_Did_I_Hit_the_10_Per_Month_Cap%3F

ChatGPT Plus has a listed price of $20 per month, but the actual cost you pay can range from about $13 to $27