I was recently promoted to SDE 2, but somehow my mind is still stuck at SDE 1, How do I start thinking like an SDE 2 ?

Its like shadi ho gyi but single wala feel aa rha, lol😂

Maybe start thinking along the lines of would an SDE2 do this? How would/should an SDE 2 do it?

This should help https://sijinjoseph.netlify.app/programmer-competency-matrix/

Interesting, i thought first you operate on a higher level for some time then only you get promoted, at least that has been in my case with all my promotions.

Fake it until you make it. Since you're already SDE2, now fake as SDE3

2-4 SDE-1 mazdooron ko munshi wale kaam pakda de, senior feel karega

Ideally you should always think 1 role ahead. Clearly list out responsibilities of sde2 ( or whatever the role is )
They might include things like

• more ownership ( maybe you start leading some meetings now instead of your manager)
• more contribution ( in terms of code? Or design sessions? Or pr reviews )
  Etc etc

If you are unclear, sit with your manager and list them and start proceeding . Also there is this concept called "managing your manager". Read about it, it will help you alot in changing mindset with role

I mean, you MAY be overthinking as companies usually almost always promote you to a level only when you’re already performing at that level

Get a right mentor/Guide outside of your colleagues or friends circle.Shifting from one level to another level will bring a lot of new expectations apart from salary increase . If you fail to satisfy the expectation then it will be difficult for you to survive.

I don't think there is much difference between sde1 and sde2 in the majority of companies. You still will be IC.