Overlay on Page Header

I added a colored box as the image behind the page header and I used the same color that is the background of our banner, but the page header appears darker. I assume there is an overlay but I can't find the css to remove it. Can you help me with that. https://saynoto5g.ca/the-risks/adverse-health-risk-of-5g/ (see the difference in color between the banner and the header block.)