ChatGPT Plus has a listed price of $20 per month but can cost anywhere from...

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

ChatGPT Plus has a listed price of $20 per month but can cost anywhere from about $13 to $27 depending on where you sign up. Differences come from taxes like VAT or GST and extra fees charged by app stores on iOS and Android