It's contractual. If you agree, you agree. Hope you've passed contracts? Has nothing to do with retainer or salaried! Even retainer agreements have non compete or cannot take alternate employment. Similarly here you agree on lock in.
Around 25k pm. They also have a policy of holding back 5-10% of your salary until you leave. Most do not get that money. Also there's a 3 years lock in. If you leave within 3 years you need to pay the firm multiple lakhs and also let go of your 5-10% held back. Very odd place.
Please share some insights? Some experienced professionals?