There can be multiple reasons for this problem. However, there are multiple solutions to resolve it too. The first and most essential factor for why is Gmail not working
is an internet connection. Since Gmail is a web-based email service, it requires stable internet to function smoothly. If your device is not connected to a secure internet connection, Gmail won’t be able to run as smoothly. You can ensure that IMAP is enabled on your Gmail account, remove and re-add your account on your device, and try the CAPTCHA reset to fix this problem.