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

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

ChatGPT Plus is listed at $20 per month, but the actual price you pay can range from around $13 to $27 depending on where you subscribe. This variation mostly comes from extra taxes like VAT or GST and the fees Apple and Google charge in their app stores