You can set the user as per https://docs.sentry.io/platforms/native/enriching-events/identify-user/, which shows

sentry_value_set_by_key(user, "email", sentry_value_new_string("jane.doe@example.com"));

This is case sensitive--needs to be lowercase user and email in the above example.

However, the Sentry UI shows user contexts with capitalization, like User, Email, IP Address, and Username

This is confusing to users.

Suggestions:

1. case should not be load bearing but
2. if it is, they should match, and also
3. if it is, this should be handled internally / just ToLower() all user, context and tag elements