You will need to install a user script manager extension to install this script.
Youtube SHORTS Disabler
It's a very simple CSS style. Possible via the :has selector in CSS4.
Simply hides all Shorts from Youtube.
This style ONLY WORKS on Chrome 105+ right now.
It can be enabled on Firefox 103+ as well:
Supported in Firefox behind the layout.css.has-selector.enabled flag
Edit the flag in about:config
Other browsers don't currently support this CSS4 feature, afaik.