My native language is Spanish. I use YouTube primarily to learn other languages so this list is not as extensive as the one I did on my English edition of my favorite YouTube channels, but I still enjoy these very much. Hopefully someone who's learning Spanish or knows the language finds them.
All of them are commentary channels surrounding different topics.
Luna Martinez (México): commentary channel that has a humorous approach. She recently opened up about an abusive relationship she was in, for almost a decade, and now is making commentary mostly through a feminist lens about problems happening in México and Latin America as a whole. Knowing what I know now, it makes her all the more compelling to me. She also speaks slowly in case anyone is still trying to get to a conversational level but can't properly hear well just yet.
Ter (Spain): She's an architect. I believe some of her videos have subtitles in English. Most of her videos are dedicated to the explanation of architecture and art. She breaks it down for people who don't know about architecture. I promise you, no one I've seen in any language has her takes. Her interpretations are very interesting to see because you never know the approach that she's going to take.
Danna Alquati (Venezuela): She makes funny commentary, mostly about terrible movies, but she also has very interesting analysis and movie recommendations. Her most popular video is an analysis on Lolita and I remember it being really good. I recommend as a whole, her series Danna Hates on Movies.
Blanca Guilera (Spain): she also talks about art but is more of an academic approach, reviewing the original intentions from artists and/or the context under which a certain piece was created.