first_notempty for boolean?

Hello, so I want to create a simple way for updating my entries and ignoring the empty variables, the easiest way I found is by using first_notempty

The problem comes when trying to do it for the boolean fields, so for them I tried using first_notnull instead which seemed a very logical option,
BUT in this case I have a records 'banned' column set to 'true'
[5zy8HGE[1].png]

Then I make a request using 'banned':''
(which in theory should simply not update the field)

And then it changes the entry to FALSE

Really not sure, so it it first_notnull not the appropriate function to use here?

Thank you 👌
[Dxi8BZW[1].png]
[wsR8Z6q[1].png]