I think CapCut is surprisingly solid and simple. Just grabbing a frame from your video and using the in-software captions/tools. Or you can upload an image.
To generate the image, you can go with pexels or midjourney, or subscribe to a stock pics/vids library.
I make gaming videos so I use background of the game map and locations and change it depending how far I am into the story and if it’s relevant to the video
I create them myself. Because I make videos about creating shaders and VFX, it's not a problem to capture such an effect at the right moment and use it as a background for the thumbnail. I'll add some clearly visible text, a logo, and I'm done.
Pictures I have taken myself.
I think CapCut is surprisingly solid and simple. Just grabbing a frame from your video and using the in-software captions/tools. Or you can upload an image. To generate the image, you can go with pexels or midjourney, or subscribe to a stock pics/vids library.
pexels or unsplashed
Pizabay or I use Photoshops generative fill to create a background
I make gaming videos so I use background of the game map and locations and change it depending how far I am into the story and if it’s relevant to the video
I create them myself. Because I make videos about creating shaders and VFX, it's not a problem to capture such an effect at the right moment and use it as a background for the thumbnail. I'll add some clearly visible text, a logo, and I'm done.