DID is a package of dissociation symptoms. It is a bit like a "level up" kinda thing. When you have "level 93 DID" you have all the symptoms of all the previous levels too. Derealization is among the "low leve"l symptoms and many, many people can experience them. I think I can even stretch it to the point that everybody will experience them at least once in their lifetime.
They are distressing though.
For me, I realized that they are linked to high levels of stress and that taking an anxiety pill when they start to become too intense, makes them more managable. I am also very used to derealization and depersonnalization (DP/DR) to the point that it really takes a high level intensity for me to feel distressed. Which is not a good thing because it means it's kinda chronic for me.
Or at least that was before my DID therapist gave me anchoring exercises to do often. I went through a period of time when "being anchored" was kinda distressing because "It's not what I am used to AAAAAA" but it's getting better now. I am better able to tell how much anchored I am and to see all of these different states as, well, different intensities of DP/DR and/or anchoring. Which makes it easier to manage.
It is an impressive symptom but not dangerous in itself. But it IS super impressive. If it is too distressing for you, do not hesitate to see with your medical team what they think could be useful for you to manage. (Anxiety pills, anchoring exercises, or anything else they think will work best for you. I do not know the whole list of stuff that work, only the list of stuff that I use for myself.)