Many thanks for your patience, it is appreciated. I am now pleased to be able to provide further assistance with your query. First of all, I am sorry to hear about the issues brought up by this. It must be a frustrating situation to be going through.
It is unlikely that this will amount to discrimination from a legal point of view as that only occurs if you are being treated differently due to a protected characteristic.
The Equality Act 2010 lists several protected characteristics, which are protected from detrimental treatment. Therefore, if someone is using any of these protected characteristics to treat someone detrimentally, that will likely amount to unlawful discrimination. They are:
- age
- disability
- gender reassignment
- marriage and civil partnership
- pregnancy and maternity
- race
- religion or belief
- sex
- sexual orientation
Here, it looks like the difference in treatment is because you are leaving so this is not going to amount to discrimination.
Even if the employer said that all employees will get the bonus, your rights to actually receive only exist if this was a contractual right, which it does not appear to be (unless you will correct me and confirm that this is something you get under your contract). If it is not, it would be discretionary and as such the employer can decide who will receive it and if they decide that those who are leaving won’t, they can do that unfortunately.