I'm getting annoying flashes on the website every time I switch to a new page with the error message > "Layout was forced before the page was fully loaded. If

I'm getting annoying flashes on the website every time I switch to a new page with the error message > "Layout was forced before the page was fully loaded. If stylesheets are not yet loaded this may cause a flash of unstyled content. content.js:84:32" Seems like a weird thing to happen on a static website. Happens on Firefox 87.0, not on Chrome.