I agree with @Nail1684 — it seems that whatever device you are using seems to be inserting unrecognized characters when you input text into a form… Could be a clue!
I asked because Notes fields can only contain approximately 7500 characters, so if the recovery key was extremely long, it is possible that this has something to do with the problem.
More questions:
- When did you create this vault item?
- When did you last modify the vault item?
- Was the recovery code saved and correctly displayed right after you added it to the vault item?
- When did you first notice the data corruption?