Working as a consultant at startup

I recently joined a foreign startup with Indian founders, but I am working as a consultant/free lancer, I'll be filling itr-4 and getting 50% exception on salary under section 44AD. They also asked me to register for GST.

If I have to switch the company in future and they ask for my PF account or ITR/salary slip, will I face any problems? I'm really unaware of all this, any guidance would be appreciated. Thanks.