Couple of things
1. don't ignore the pinned post in this forum regarding posting a OBS Studio streaming/recording log when asking for support
2. you don't mention your specific capture device, and the settings you are using for it. which is most likely (??) highly relevant
My general rule of thumb is to get Audio and Video source working outside of OBS Studio (OBS Studio NOT running at all). Use Operating System (OS) native tools (ex Windows Recorder) to ensure your basic sources are working at OS level. only then configure in OBS Studio
Also, in case you are unfamiliar with working on Video sources in OBS, you may have mistakenly stretched the source (from an edge) vs resizing from a corner?? You can right-click on Source and Transform -> Rest to make sure you didn't stretch the video source unintentionally. The Help section on this site has info on working with Sources that goes into more detail