Is my experience with reading common?

My (TL) is French. At the moment, I feel that there are a lot of resources that I can read no problem. For example, I can read the French Wikipedia articles for whatever I'm looking for, I tend to prompt AI in French and read its responses in French, I can read cooking blogs and certain news sites. It does take me a little bit to do it, and I'm not nearly as fast as I am in English, but I get more than just the gist of the article, probably 95% of the words and almost all of the meaning. It is as though if English suddenly went away tomorrow, and these were all that I had to use in my daily life and job, I'd be slow but fine.

HOWEVER! There seems to be like this...second tier of written materials that is just like, "F you, we're speaking *French* and you are absolutely not someone who does that". I can't really explain it other than to say that when I try to read one of these resources, it's almost as though the language is totally different. I get maybe 50% of the uncommon words, the grammar is intense, the sentences are nuanced, and effectively I have no idea what they are saying. I kind of don't get it - I feel very confident with many of my resources, but then I see these other ones and it's as though I haven't studied the language at all.