People who purchased Nano S devices in 2017 are starting to see first issues now, that means cheap display is probably meant to last 4 years more or less.
Ledger warranty is two years and they are not responsible for your device after that, but like I said you can fix this ordering new display for $2 or $3, don't waste any money purchasing new ledger.
However, there could be an issue with their new closed source firmware breaking devices, like this guy reported few days ago (post is being downvoted on purpose):
I don't want to transform possible coincidences into conspiracies. While it may be possible, a much easier explanation is that those components are cheap and made so. It's the current consumerism era's fault.
However, it's their loss. While I am not sure I'd be capable of changing that display myself, I am
pretty sure that I will no order HW from them again.
I'll keep in mind next time I power the Nano S to reduce the brightness. Thanks.