Technically, your two columns are perfectly aligned with each other.
Since the input is inside a group of forms, it gets an extra height compared to the clear button.
If you remove label="Filter" from your code, you will see the correct alignment.
The only thing I see now is to give the button margin-top: 25px; .
Here is a demo
Basically, I gave a custom class to a button, and in css I added a margin that I needed to align.
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