The listed ChatGPT Plus price is $20, but real costs vary from $13 to $27...

https://tango-wiki.win/index.php/How_Early_Should_I_Cancel_ChatGPT_Plus_to_Avoid_Being_Charged%3F

The listed ChatGPT Plus price is $20, but real costs vary from $13 to $27 depending on where you buy it. Differences come from taxes like VAT or GST and extra fees charged by app stores