I had my car checked at the garage they said the breaks were fine and They lubricated the callipers but the sound has now come back after a few weeks since doing this. The sound happens when I am braking only
Did you have the brakes replaced somewhere other than the dealership and with pads and/or rotors that were not OEM? This is very common with aftermarket brake parts and sometimes factory parts too but mostly aftermarket. It doesn't generally indicate a performance or safety however can be very annoying. If you've had them inspected and told there is still plenty of pad material remaining then most likely the only way to correct it would be to have the rotors and pads replaced. If you used aftermarket parts I'd recommend not using those parts again otherwise the squeaking will just come back when the pads and rotors glaze again from the heat.
Glazing is a common occurrence and can manifest itself by the constant squeaking you hear. Because brake pads and rotors are a wear item and damage caused by excessive heat like warping and glazing in most cases is considered wear and tear. Make sure the repair facility knows you are still experiencing issues. Sometimes it takes a couple of tries to diagnose but they should be able to identify the issue and give you options to correct it. They need to rule out safety issues and identify if it is in fact the brake pads making the noise. It may include replacing the pads and rotors. If your driving conditions are such that this issue reoccurs you may want to look at a high performance brake material. High performance brake material can withstand higher temperatures than the brakes used in normal passenger car applications. Ask the Toyota dealer if they have TRD* or other options for your vehicle. Hopefully you find this information helpful.
*TRD stands for Toyota Racing Division. TRD parts and accessories are available at the Toyota dealer.