Personal Hide YouTube Shorts Extension - load as an unpacked extension in Chrome or in about:debugging in Firefox - style rules extracted from https://soitis.dev/control-panel-for-youtube

manifest.json

{
  "manifest_version": 3,
  "name": "Hide YouTube Shorts",
  "description": "Hides YouTube Shorts",
  "version": "1.0",
  "content_scripts": [
    {
      "matches": [
        "https://www.youtube.com/*",
        "https://m.youtube.com/*"
      ],
      "exclude_matches": [
        "https://www.youtube.com/embed/*"
      ],
      "css": [
        "style.css"
      ]
    }
  ]
}

style.css

/* Desktop */
@media (hover: hover) {
  /* Side nav item */
  ytd-guide-entry-renderer:has(> a[title="Shorts"]),
  /* Mini side nav item */
  ytd-mini-guide-entry-renderer[aria-label="Shorts"],
  /* Grid shelf */
  ytd-rich-section-renderer:has(> #content > ytd-rich-shelf-renderer[is-shorts]),
  /* Group of 3 Shorts in Home grid */
  ytd-browse[page-subtype="home"] ytd-rich-grid-group,
  /* Chips */
  yt-chip-cloud-chip-renderer:has(> #chip-container > yt-formatted-string[title="Shorts"]),
  /* List shelf (except History, so watched Shorts can be removed) */
  ytd-browse:not([page-subtype="history"]) ytd-reel-shelf-renderer,
  ytd-search ytd-reel-shelf-renderer,
  /* List item (except History, so watched Shorts can be removed) */
  ytd-browse:not([page-subtype="history"]) ytd-video-renderer:has(a[href^="/shorts"]),
  ytd-search ytd-video-renderer:has(a[href^="/shorts"]),
  /* Under video */
  #structured-description ytd-reel-shelf-renderer,
  /* In related */
  #related ytd-reel-shelf-renderer {
    display: none !important;
  }
}

/* Mobile */
@media (hover: none) {
  /* Bottom nav item */
  ytm-pivot-bar-item-renderer:has(> div.pivot-shorts),
  /* Home shelf */
  ytm-rich-section-renderer:has(ytm-reel-shelf-renderer),
  ytm-rich-section-renderer:has(ytm-shorts-lockup-view-model),
  /* Subscriptions shelf */
  .tab-content[tab-identifier="FEsubscriptions"] ytm-item-section-renderer:has(ytm-reel-shelf-renderer),
  /* Search shelf */
  ytm-search lazy-list > ytm-reel-shelf-renderer,
  /* Search */
  ytm-search ytm-video-with-context-renderer:has(a[href^="/shorts"]),
  /* Under video */
  ytm-structured-description-content-renderer ytm-reel-shelf-renderer,
  /* In related */
  ytm-item-section-renderer[section-identifier="related-items"] ytm-video-with-context-renderer:has(a[href^="/shorts"]) {
    display: none !important;
  }
}