The listed $20 price for ChatGPT Plus often varies between $13 and $27...

https://suprmind.ai/hub/chatgpt/pricing/chatgpt-plus-price/

The listed $20 price for ChatGPT Plus often varies between $13 and $27 depending on your location and platform. This difference mostly comes from taxes like VAT or GST and extra fees added by app stores on iOS and Android