we at 3ipunt have checked that the cookies are not being sent successfully in Chrome 80.
We found the problem in LTI activities, but everything that requires a cookie could be affected too.
This behaviour was introduced first in https://tracker.moodle.org/browse/MDL-67175
Steps for reproducing the error:
1 - Access a course
2 - Create an external tool activity (LTI)
3 - Select 'Embedded' as visualization type
4 - Click in the activity
Moodle shows the login page of the provider LTI, instead of logging the user into the LTI provider.
The cookies that are being sent are not marked with 'SameSite, Secure' flag so Chrome 80 rejects them.
It has been tested in both 149 and 162 Chrome 80 version, working on 149, but not on 162.