ChatGPT Plus is listed at $20, but the actual price you pay can range from...

https://wiki-aero.win/index.php/What_Is_the_Max_File_Size_for_ChatGPT_Plus_Uploads%3F_A_Deep_Dive

ChatGPT Plus is listed at $20, but the actual price you pay can range from about $13 to $27. This happens due to taxes like VAT or GST and extra fees charged by app stores on iOS and Android