Set a timer right before you open the app - not after, but before. Sounds obvious, but it works precisely because it triggers awareness: when you know the countdown is already running, your brain at least occasionally notices the time. Without a timer, our brain gets caught in a loop of variable reinforcement - every video could be super interesting, so we can't stop, we're waiting for magic in the next one.
The catch is that people often suggest just deleting the app or starting a 10-step routine. In reality, that kind of thing doesn't work for long - motivation crashes after a couple of weeks. It works better when you don't forbid yourself TikTok, but change one thing: that five-minute scroll before bed. Try five minutes of an audiobook, a podcast about something relaxing, or just scrolling through photos on your phone instead. Your brain gets the same "quick content," but it's not designed to keep you hooked for another two hours.
And yeah, move TikTok off your home screen and turn on screen time in settings - not a block, just a reminder. When the app asks for five more minutes and you have to tap yes, that's a second of pause that might save your sleep.