A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
Your formula returns more then one value, means it returns an array. This array (the values) are filled in the cells and you see the blue border around. Here is the article: https://support.microsoft.com/en-us/office/dynamic-array-formulas-and-spilled-array-behavior-205c6b06-03ba-4151-89a1-87a7eb36e531
Change your formula to return one one value and you get the expected behavior.
Andreas.