Hello,
Chrome uses several tasks and services, which might be the cause. Uninstall your Chrome, then go to Google and download the latest release, re-install, during install it will have the Make Chrome your default browser already check marked. This should fix your problem.
You can also refer to the following link.
https://winaero.com/blog/prevent-windows-10-from-resetting-your-default-apps/
(Note: This is a third-party link and we do not have any guarantees on this website. And Microsoft does not make any guarantees about the content.)
Best regard,
Sylvia