What if you are reading an interesting book ? I think it would be a great way to train your attention to the level it used to be.

And if you can’t even do that, I suggest you start reading a book right before sleeping until you pass out. Every night. You will fall asleep extremely fast at beginning but I managed to get back to reading while having extreme difficulty concentrating from a completely different illness than TikTok. It only took 2 years.