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

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

ChatGPT Plus is listed at $20, but the actual price you pay can vary between $13 and $27. This difference comes from taxes like VAT or GST and extra charges from app stores on iOS or Android