one thing to avoid is lazy loading the Logos as this can cause a shift.
Most lazyloader plugins allow you to exclude images with a specific CSS class. For the GP logos you can use: is-logo-image
Had a quick nose around the site to see what else may be causing this. The main issue is the font loading, on initial load it uses a fallback font and after rendering the actual font loads causing a shift. What cache plugin are you using ? Some of them i believe offer the option to preload fonts to stop this from happening.
I’ve disabled it and submitted the valid test to Google Search Console but they said it will take 28 days to validate. Can you check (or tell me how to check) to see if disabling the FontAwesome plugin fixed the issue?