Don't let AI pick your thumbnail alone
Some tools can pull a handful of frames from your video and suggest which one might work best as a thumbnail, based on things like faces, contrast, or motion. It is a fast way to skip scrubbing through a whole video looking for a decent frame, and the suggestions are often a reasonable starting point.
But a thumbnail is a judgment call about what will make someone stop scrolling, and that decision depends on context the tool cannot see, your audience, your platform, what else is on the page next to it. I've picked a frame the tool never even suggested more than once. Treat the suggestions as options, not the final answer.
Try this today: pull a set of suggested frames from your next video, then pick the one you would choose without the tool's help, or grab a completely different frame if none of the options feel right. The tool should narrow the search, not make the final call for you.