KDL filter to exclude results with character?

Hello people of the internet

I am trying to create a field filter in kibana that excludes and results including the ? character

After an application update we have log results for domain\username? and domain\username , we wish to exclude the results including ? as they are messing with the reports.

Reading around it is suggesting that something like "not fieldname.keyword "*?" " or *\? should work but I still see results with ? included in the search hits, no error is returned

Allow leading wildcards in query is enabled and we are running ELK 7.14

Any help would be appreciated