Actually K2 is compatible with php 8 since January 2023:
getk2.org/blog/k2-v2-11-rolling-releases-joomla-4-and-more
I have try to use php 8 on the website and the k2 is working well with Joomla's stock template.
The YT Plugin is the one that breaks the compatibility. Actually even the backend fails to white page when YT plugin is active.
Therefore i need support for YT framework and , maybe SJ modules that take info from k2: database SJ k2 Filter, and other.
Are you plan to update YT framework? Let me know so i can switch to another framework, and another template.