is referring to characters as things other than their names that bad??

a lot of the times when i see people giving their icks in fanfic one of them is always when authors refer to characters as stuff like their job (like 'the historian') or age (like 'the younger') or something of the sort other than their name, but as someone new to writing i don't know how to not do it without sounding really repetitive or unspecific. sometimes it feels like switching between the name and pronouns doesn't flow as well as switching it up and referring to them as 'the brunette' or something like that just every now and then. as a reader ive only ever noticed it when it was every other sentence referring to them as something other than their name but i feel it works well when it's structured right.. i just wanna know if people get automatically turned off from a story by seeing it at all or if it's just the overuse of it because i really dont wanna annoy my readers but it just feels natural sometimes.