If you edit your profile on a Stack Exchange site, does Stack Exchange keep records of your old profile data?
Moderators can see your previous display names if they need to. This is the most widely seen thing that you can change in your profile as it's displayed against all your questions and answers. Most other editable fields are only displayed on the profile page itself.
Public information from your profile will also be temporarily accessible via the Stack Exchange Data Explorer. It's in the
Users table and your
ID appears in the URL of your profile.
https://meta.stackexchange.com/users/547450/user ^ id
If your question relates to accidentally having deleted some data from your profile that you want back, this could be helpful, since it's only updated once a week (every Sunday morning around 3:00 UTC, to be exact).