The real problem: the URL changes every time
When you put a direct link in your TikTok bio, it points at one thing. The moment you want to push something else, you have to edit your bio, which takes time and makes every old post that referenced the previous link out of date.
On top of that, TikTok gives you a single field: you cannot keep the old link and add the new one. You overwrite it every time. Over months, that is a steady source of mistakes and lost clicks.

