Brown coolant

The brown is likely from rust. You need to flush the system and install new anti-freeze at a 50/50 ratio with water or if your area is really cold go with the recommendations on the anti- freeze bottle.

Looks like rusty green anti-freeze to me. Not severely rusty but enough that it is time for a flush.

Flush it see if it returns, Check the transmission fluid and oil for same color and low levels.

coolant has to be changed every now and then- brake fluid must be changed sometimes- oil has to be changed occasionally- this is called maintenance- hopefully, it's not a blown head gasket-