I feel like it's okay for some of your videos to be more sombre or serious. You can't expect all of your videos to be super fun and upbeat all the time, That's a lot of pressure to put on yourself! You may not be satisfied with the mood of the videos but how do you feel about the content? I feel like if you are happy with how you've conveyed the message then it's definitely worth posting.
The video's I've watched in the past that are more serious and approach a topic someone cares about a lot are the ones that have stuck with me so maybe it could help with growing your channel rather than have the opposite effect
(On a personal note, I'm always satisfied when I upload a video then two days later I'll look back and realise I missed something or made a mistake and kick myself to the moon)