Curve25519 is designed to be resistant to timing attacks, such as clamping the 254th bit in x25519 keys to 1 so that implementors can not optimize away a multiplication round.
That doesn't mean that this implementation doesn't have timing attacks, but the implementors claim they chose mechanisms which should be constant-time.
That doesn't mean that this implementation doesn't have timing attacks, but the implementors claim they chose mechanisms which should be constant-time.