The stable version of Nginx that supports http/3 is expected to become available in April 2024. This is when it makes sense for Plesk to also offer http/3.
From articles that foster the hype about http/3, it sounds as if it can increase a website's speed incredibly much. On average, on real website tests by several reknown sources, the acceleration has been seen at around 0.2 to 0.3 s/page, typically around 12 % improvement compared to http/2, but it depends on the actual website content. Most website owners will be able to increase the speed of their sites dramatically more by reviewing the scripts/plugins/themes they use, because most issues of slow websites are caused by bad software.
