Portraying good leadership skills in an email

Imagine that you have an exemplary team member who deserves a 20% raise based on their performance and dedication during the Covid-19 pandemic. You would love to give them the raise they deserve, but there isn't room in the current budget because of the belt-tightening your company had to do during the Pandemic.
Write an informal email to this team member thanking them for their stellar performance. Tell them in the email that you wish you could give them the raise they deserve, and then explain why you cannot. Finally, offer them assurances that a raise will be approved once funds are available.
Think about the best way to relay this information to the team member. How can you demonstrate good leadership skills in the email?