Do you mention levelsfyi or Glassdoor when negotiating salary?

Yes

I usually tell them I’m a Top Contributor on Blind and then, sensing that negotiation is futile, they just give me top of the band.

Why wouldn't you?

I dont mention the source but i do say i have a pretty good accurate source and know the pay band already

And then they hit us with the “but we aren’t FAANG so we can’t pay like FAANG”

Both. I tell them frankly what I want and will accept