Filter array of objects by comparing it with another array of objects

I have an array of objects coming from backend as shown below.

let input  = [
    {month: "Dec", count: "45"}, 
    {month: "Mar", count: "12"}, 
    {month: "June", count: "5"} 
]

The below variable dropdownValues is the ones selected by user on frontend dropdown.

let dropdownValues = [ 
{key: 'Mar'}, 
{key: 'June'} 
]

so considering user selected Mar and June in dropdown, we want the input variable to only select those keys and compare it with month property of input and remove the other objects.

So the final output based on dropdownValues should look like this

output = [ 
    {month: "Mar", count: "12"}, 
    {month: "June", count: "5"} 
]

In order to achieve this result, i tried doing the following but it doesnot filter out Dec month object.

let output = input?.filter((el) => {
        return dropdownValues.some((f) => {
          return f.key === el.month;
        });
      });

can someone let me know where i am going wrong with this.