Need to know if it's safe!

20M here. I just got back from a mountain trip few weeks ago and came home with crazy acne and a ton of tanning (I had never used sunscreen until a few weeks ago).

My natural tone is the average light-brown Indian shade on my face/arms, but about 4 shades lighter everywhere else. I started tret about 3 weeks ago. At first it was rough because I was using it OTC without a prescription from a doc every day (pea-sized amount). Pharmaceuticals are super cheap in India and nobody really cares about prescription rules, so getting the drug itself is ez. I’ve now reduced it to 3x a week.

The good part: my acne has gone down a lot, and my face is about 2 shades lighter somehow....is that normal? which is tbh amazing. A friend suggested I add azelaic acid to my routine is that actually a good idea?

My main goal now is to get back to my original skin tone and get rid of the childhood tanning.

PS: I fly on a daily basis for work, so please suggest something that won’t make my skin flake like crazy the way tret did at the start.