Google will release chrome 80 in mid Feb 2020. In it is a significant security enhancement related to cookies and protection and some sites that have yet to ensure compatibility may have their users reporting issues.
You can find out more here ( https://blog.chromium.org/2019/10/developers-get-ready-for-new.html ) and see the additional information available at these related links. For a developer perspective, check out this link ( https://web.dev/samesite-cookies-explained/ ).
For specific instructions on testing your site, see this link ( https://www.chromium.org/updates/same-site/test-debug )