YouTube adds an overlay* in the upper left corner which says "Includes paid promotion". The overlay leads to https://support.google.com/youtube/answer/10588440

Also creator added "#sponosred" hashtag.

Both "Includes paid promotion" overlay* and "#sponsored" hashtag can be detected and therefore the video could've been skipped or hidden by some extension or by uBlock Origin filter. You can either rely on detecting aforementioned Google overlay* or sponsored hashtag.

*HTML code of "Includes paid promotion" overlay:

<div class="ytp-paid-content-overlay" aria-live="assertive" aria-atomic="true" data-layer="4"><a class="ytp-paid-content-overlay-link" target="_blank" style="display: none;" href="https://support.google.com/youtube?p=ppp&amp;nohelpkit=1"><d... class="ytp-paid-content-overlay-icon"><svg fill="none" height="100%" viewBox="0 0 24 24" width="100%"><path d="M6 9H5V5V4H6H19V5H6V9ZM21.72 16.04C21.56 16.8 21.15 17.5 20.55 18.05C20.47 18.13 18.42 20.01 14.03 20.01C13.85 20.01 13.67 20.01 13.48 20C11.3 19.92 8.51 19.23 5.4 18H2V10H5H6H7V6H21V13H16.72C16.37 13.59 15.74 14 15 14H12.7C13.01 14.46 13.56 15 14.5 15H15.02C16.07 15 17.1 14.64 17.92 13.98C18.82 13.26 20.03 13.22 20.91 13.84C21.58 14.32 21.9 15.19 21.72 16.04ZM15 10C15 9.45 14.55 9 14 9C13.45 9 13 9.45 13 10H15ZM20 11C19.45 11 19 11.45 19 12H20V11ZM19 7C19 7.55 19.45 8 20 8V7H19ZM8 8C8.55 8 9 7.55 9 7H8V8ZM8 10H12C12 8.9 12.9 8 14 8C15.1 8 16 8.9 16 10V10.28C16.59 10.63 17 11.26 17 12H18C18 10.9 18.9 10 20 10V9C18.9 9 18 8.1 18 7H10C10 8.1 9.1 9 8 9V10ZM5 13.5V11H3V17H5V13.5ZM20.33 14.66C19.81 14.29 19.1 14.31 18.6 14.71C17.55 15.56 16.29 16 15.02 16H14.5C12.62 16 11.67 14.46 11.43 13.64L11.24 13H15C15.55 13 16 12.55 16 12C16 11.45 15.55 11 15 11H6V13.5V17.16C8.9 18.29 11.5 18.93 13.52 19C17.85 19.15 19.85 17.34 19.87 17.32C20.33 16.9 20.62 16.4 20.74 15.84C20.84 15.37 20.68 14.91 20.33 14.66Z" fill="white"></path></svg></div><div class="ytp-paid-content-overlay-text">Includes paid promotion</div><div class="ytp-paid-content-overlay-chevron"><svg height="100%" version="1.1" viewBox="0 0 32 32" width="100%"><path d="m 12.59,20.34 4.58,-4.59 -4.58,-4.59 1.41,-1.41 6,6 -6,6 z" fill="#fff"></path></svg></div></a></div>