Accidental email linkage to user accounts.

### Environment

SaaS ([https://sentry.io/]())

### Steps to Reproduce

Hi,

A user wrote in [here]() about an accidental email linkage to user accounts.
They were attempting to invite a member to the org, but they were getting an error stating they're already a member.

While the problem has been resolved, the reason behind the email address mix-up is unknown.

More details can be found in this [internal ticket]().

### Expected Result

Different email addresses are not tangled with one another.

### Actual Result

Different email addresses were tangled with one another.

### Product Area

Other

### Link

*No response*

### DSN

*No response*

### Version

*No response*

The issue names no repository files, tests, or entry points. Start with the linked Linear investigation and the reported invite/member reproduction; done means identifying why distinct email addresses became linked and documenting or implementing a verified prevention.

Written by the indexing model from the issue text.