Hey! (This is my first post on "feedback" sub-forum, so hope to be an actual help intead any other thing.)
First of all, and to be honest, they're both great! I do like the dark on them, and I think they were well chosen/created. Although, I do think your banner could just have another font, maybe more "unique", if I can say so. But, it's really important to be aware that some fonts can't be used for this purpose, our YouTube channels, because they're copyright. I'll try to post here a link of one of my favourite font website that are actually royality free fonts and you can use them (I can't find it now, but I will!).
Now, the end card. It is awesome! Really simple and, yet, really creative. I must ask, the fox drawing is a creating of yours? If yes, I'll let you with a idea: it should be good to see some movement on that end card, for instance, with one/two more frames, with really subtle and slow transitions between them, in order to make it a little more dynamic.
But, as I said, these are my ideas. Overall, I think this is a really great job! I would like to have something alike on my channel... or even part of that creativity.