ChatGPT Plus is officially $20 per month, but the actual price you pay can vary...

https://remote-wiki.win/index.php/Are_Modified_Android_Apps_Real_ChatGPT_Plus_Access%3F

ChatGPT Plus is officially $20 per month, but the actual price you pay can vary from about $13 to $27. This happens because taxes like VAT or GST and extra fees from app stores add costs