After being annoyed by this (and a handful of persistent others) a few too many times, I ended up with the following ublock rules:

    www.youtube.com##ytd-rich-grid-media.ytd-rich-item-renderer:has(a[href='/@MrBeast'])
    www.youtube.com##ytd-rich-grid-media.ytd-rich-item-renderer:has(a[href='/@BeastReacts'])
    www.youtube.com##ytd-rich-grid-media.ytd-rich-item-renderer:has(a[href='/@BeastPhilanthropy'])