solder iron tip issues
There are definite quality differences between tips from different vendors, the base material used may differ (steel, iron, copper, silver) - Though I don't generally support silver as it gives near to no benefits over a well coated copper one, I have recently posted an answer on that here. But there is also difference in coating quality and even type and some last longer than others.

What you should never do with any coated tip (99% of them) is clean them with hard abrasives. Very cheap tips might not even like those steel mesh sponges, but if your tip is that cheap...

Which brings me to another piece of advise: Try if you like a steel mesh sponge, many outlets have them at a buck or two, they need no wetting and if you can get the movement right easily they clean well enough, but at 350degrees offer a much lower chance of cracking of the coating. But those are not for everyone and in many cases a lightly wet sponge (not soaking! Very easy to crack the coating when it's soaked) cleans better.

To restore a coating there are things like "Tip Activator" that you can use. A small $8 can from cooper tools / weller can last you dozens of uses and for most people you only need it once per year, or even longer for each tip you use regularly. It basically cleans a little and leaves a bit of coating layer extra behind. But never use it on a new tip of well coated quality. As with anything, a cheap home solution to add coating or such is always less good than a good factory coating.

You may be able to restore your damaged tip to sort of working order with tip-activator as well, I have used it to get horrible uncoated stainless steel tips to usable for a month or two, so it's worth a try.

Usually tip-activator works best when you put in a tip at 150 ~ 200 degree C, but the datasheet or booklet that comes with it will say how to use it.