So your 'test' of tiktok was mostly invalid. It takes a few days for "The Algorithm" to become astonishingly good at finding things for you to watch.

TikTok also seems to 'run out' of new material to show you easily. This makes sense, mathematically -- there just isn't enough new content to avoid repeats and quality drop if you view it for hours at a time.

You will get more interesting content that appeals to you if you interact with the app honestly, instead of grabbing someone else's phone for a few minutes and then trying to prove whatever point you're on about here.