Beep boop, I’m a bot! I dug through the forum to get you started. I sometimes get things wrong though, so do with this what you will until a human has a look.
Both of the files that fail have “chat” in the URL: /assets/css/chatbot.css and /assets/img/chatbot/chat.png. global.css has no such keyword and loads fine. That fits an article I found, which lists “chat” as a keyword that’s automatically blocked in URLs and gives a 403 Forbidden.
Renaming the files and the folder should fix it. Use something without “chat” in the name, like assistant.css and /assets/img/assistant/. Then update the paths in your HTML and CSS to match.
The article’s section 3 covers blocked keywords:
The article also says renaming doesn’t change the rule that hosting live chat scripts is prohibited. If your chatbot is a live chat, renaming the files won’t make it allowed.