To block Google's before you continue popup on the main Google site add the following lines to uBlock Origin's My filter tab:
src - https://www.ghacks.net/2020/09/27/how-to-deal-with-googles-and-youtubes-aggressive-popups-before-you-continue-sign-in/
JavaScript:
www.google.com###lb
www.google.com##:root:style(overflow-y: visible !important;)src - https://www.ghacks.net/2020/09/27/how-to-deal-with-googles-and-youtubes-aggressive-popups-before-you-continue-sign-in/