Unfortunately, this is probably not discrimination in the legal sense. From a legal standpoint, discrimination is only actionable through the court system if the employer's motivation for engaging in it is a legally protected trait, such as one's race, religion or disability. It's the MOTIVATION that matters.
For instance, if it could be prove that an employer had a standing policy to pay men 20% more than women simply because they were men, that would be illegal discrimination. However, if an employer decided to arbitrarily pay employees who drive SUVs to work 20% more simply becuase they drove SUVs, that would not be illegal despite being unfair and ridiculous because the car one drives is not a "legally protected trait."
So, if you have prove that your employer is motivated by a legally protected trait here, you might have grounds for a discrimination claim. But if this is unfairness based on anything else, it would be legal despite being a poor practice.
I hope that you find this information helpful. Please do not hesitate to let me know if you have any questions or concerns regarding the above and I will be more than happy to assist you further.
If you do not require any further assistance, please be so kind as to provide a positive rating of my service so that I may receive credit for assisting you. Very best wishes moving forward.
* Disclaimer *
Just Answer is a venue for informational and educational purposes only. No attorney-client relationship is formed by these communications.