ChatGPT Plus lists at $20 a month, but the actual price you pay can vary from...

https://www.slideserve.com/aaron_ward92/why-does-chatgpt-plus-cost-more-on-android-than-on-the-web

ChatGPT Plus lists at $20 a month, but the actual price you pay can vary from about $13 to $27. This difference happens because of extra taxes like VAT or GST in your country and fees added by app stores like Apple or Google