Firefox streams better than opera

Using the same laptop and screen, and with the out-of-the-box settings, I get better images (like more details, brighter) when streaming with firefox in comparaison to streaming with opera
Is there any technical reason reason for this?
Is it just that for opera I wouls need to adjust windows or screen's settings?

Do you have " sharpen videos on all sites" selected within opera? Shot from opera one portable:
Firefox is my default. I also use Vivaldi standalone and librewolf portable. Never really paid much attention to any of them concerning video quality.