Managing a date variable in Excel for filtering in Power Query

Using the variable, I filter for all data earlier than April 31st or month 4. I created a table in Excel, imported it into Power Query, and used a drill-down to get the parameter. My problem is that the drill-down creates a list, and when I try to use the variable to filter, Power Query returns an error because this type of processing isn't possible on a list. I tried to solve the problem with Copilot, which suggests transforming the list into another format within the code, but nothing works. Have you encountered this problem, and what solutions do you have? Thank you.