ChatGPT Plus is listed at $20 a month, but the actual price 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 a month, but the actual price can vary between about $13 and $27 depending on where you subscribe. This difference mostly comes from extra charges like VAT or GST and fees added by app stores on iOS or Android