Power Automate - Filter Query by a Field that is blank

Hello,

I am currently building a flow for my institution's waste pickup program where an email is sent out that accumulates a table of any requests (from Sharepoint) that have not yet been completed. There is a field in my Sharepoint list called 'Date Completed'. In the 'Get Item' step of my flow I want to Filter Query 'Date Completed' eq 'Null', but I keep getting an error message. See flow and error message below:

"String was not recognized as a valid DateTime. Creating query failed.
clientRequestId: c33d3be3-bf61-41b8-ab1b-b508a7b0317c
serviceRequestId: c33d3be3-bf61-41b8-ab1b-b508a7b0317c"