[Dayshine]

"we validate a method proposed by various authors before"

Does this mean you expect them to add additional analysis to their paper evaluating it against your unpublished work? That's what validating would involve.

I can see an argument for dropping the word novel, but it's a bit semantic as their approach is slightly different and your work isn't part of scientific literature.

I can't see how adding a sentence referencing your work would make sense as it didn't contribute to theirs, and they did not assess it. It would simply confuse. The omission of your work makes it clear they didn't know about it while doing theirs, which provides the accurate context.