Not a proper workaround, there s more to this issue! This paid extension is a scam in the 1st place since all it does is opens the link in another browser which you can do nicely on your own without paying 2+ euros!
more importantly NO OTHER BROWSER I know off except Safari can display proper color in youtube on all modern wide gamut mac displays. No other browser supports color management for video (including chrome and firefox), so you get 4k but you also get weird oversaturated tones.
bottomline - you cannot watch youtube in HQ on ANY MODERN mac computer, thank you Apple for being so petty!