There are times when the wallet address you copied becomes different after pasting it to the text field, and this is because of some malicious software installed on your computer.
Here's what you should do to prevent this from happening:
- Check if there's a malicious browser extension or some sort of other malicious software installed on the user's computer that monitors the clipboard for bitcoin addresses and replaces them
- Carefully scan your browser for extensions and scan your PC with an anti-malware tool
- Always double-check the wallet address before hitting "SEND" as these transactions are irreversible—read this article for more information