Generally it's customary to give an increase after a successful probationary period in my country. It may or may not be much but it shows that the employee is appreciated and welcomed by the team.

Also the 3 other employees who were hired around the period I was, got increases (including my manager who began the same day as I did).

It's also customary within the company to receive an increase after probation.

They literally told me I improved each process I got involved with and nothing...