Thank you @RabBit_BR and @Christian_Dahlqvist for helping me with this.
After following @Christian_Dahlqvist advice I was able to resolve this issue.
Since this is mapped dynamically, I needed my query to be written as the following:
filterQuery.Add(fq => fq
.Bool(f => f
.Must(boolSHould => boolSHould
.Term(t => t
.Field(feild => feild.DOI.Suffix("keyword"))
.Value(value))
))
);