I have no idea what the blacklight mode is for, but it’s a feature.
You can check if banknotes/driving licences* are counterfeit, and if you turn the lights off in your bathroom and then look at the toilet with the blacklight, you’ll be more thorough when you clean it!
Just realised, you could use it in hotels as well :-(
- We have a desk mounted one at work as part of security checks on check driver’s licences.
I never understood why some people insist on owning property. Especially more than one. Never really able to afford it myself. The Army (UK) cushioned me for a while and then when I left, there was no way to get a mortgage. Maybe if I’d saved instead of enjoying myself. Too late now though.