The straight holder ferrules are usually made of ferrous metal , which tends to rust over a period of time, and based the weather conditions like humidity , moisture etc, Unless you have one of those steel ones from Yoke Pen Co. You can get it here https://www.yokepencompany.com/collections/accessories/products/straight-pen-holder-nib-ferrules. Even inks can cause damage to these ferrules. If taken right care of , these ferrules could last for a long time .
In the event of the ferrule getting damaged for whatever reason. It could be replaced with a new one. I don’t know much about other pen makers but I tend NOT to stick the ferrule to the straight holder and can be easily pulled out for storage when not in use or for general maintenance.
General Maintenance :
* Remove the ferrule from the holder when not for prolonged period , spray it with some anti-rust (WD40) and store it separately.
* If the ferrule on you holder is fixed then at least spray some anti-rust on it at intervals (once in a couple of months)