Your pipe may be pinched. Bracket holding rubber supply hose may have built up rust in it. Hot day makes the pipe pinch worse. When you apply brakes it forces a lot of pressure but the return when letting off the brakes not so much. Be careful when prying the bracket open. Don’t nick the line. Don’t damage the ABS wire. Don’t hit your face. The flat head screw driver will slip off. Clean rust out and let the pipe slide then tap it slightly closed with a hammer. Happy free fix.