ChatGPT Plus lists for $20, but actual prices vary from around $13 to $27...

https://wiki-book.win/index.php/Why_Does_ChatGPT_Plus_Cost_More_on_Android_than_on_the_Web%3F

ChatGPT Plus lists for $20, but actual prices vary from around $13 to $27 depending on your location. This happens because taxes like VAT or GST get added, and app stores on iOS and Android often charge extra fees