Update: Repeat again: No interest to read technical. from my view of point as an user I see the addon fails to work on websites in one browser and works perfectly in others.
So it is the work of technical specialist (the addon creator) among others technical specialists (browser computer programmers).
Please do not reply just as to reply and make some one the victim. Just solve the technical problem on your side.
Thank you and I hope you will be more carefully to read user review because most users are professional not in your area.

Mix together two programs functionalities leads to wrong way working tool.
I tried to send email to developer but got infinite sign up..sign up . I am just user one of most people whom programmers create software. No interest to read technical. Please check this link it works perfectly in Chrome and broken in Firefox (no flyer to see), Chrome 84 /Firefox 68. Windows 64 English. ublock installed by default only, no any other addons/extensions.
URL: https://www.nofrills.ca/print-flyer?navid=flyer-deal&navid=Flyer-and-Deals