Wow, this looks really beautiful! I'll give some advice. I think the facial shading is very nice and clean. The highlights and shading are all where they are meant to be! But for darker toning, I suggest adding maybe a lightly opaque dark blue in areas such as the neck and under Miraculous' mask.
The hair, while shaped really well, can be a bit sharper as you mentioned! I haven't watched the play back so I wouldn't know how you did it, but try sketching and colouring a layer under the sketch to shape the hair, and then on a layer above the sketch and volume, lighting and shading, and erase the sketch where necessary.

I hope this helps! Good luck on future drawings! I really love your art and to me, you are such an amazing artist!

Thanks a lot, I really appreciate it! You mentioned some really helpful pointers that I will keep in mind for later use :))