This is a strategy I've developed to stop myself from mindlessly scrolling. Opening my phone and opening an app is basically an automated physical response like walking at this point, I don't think about it. It even is an automatic stress response to pull out your phone to hide from the world when you get anxious.
I found it helps to make your more intrusive apps harder to get to, even something as simple as removing TikTok from your home screen so you have to do that extra step of pulling it up from your app drawer to get to.
In combination with that, I try to catch myself mindlessly scrolling and stop and think, "what am I trying to do right now?" Often the answer is nothing, it's mindless. That helps me pull myself out of automation mode to stop.