Possible to save multiple logs for same email using different letter case

[jmauzyk]

Describe the bug

If a log already exists for a specific variant ID with an email address (e.g., [email protected]), any attempt to register interest again using the exact same email address fails validation, as expected.

However, if the same email address is entered with different letter casing (e.g., [email protected]), it is saved as a new record. This behavior can result in duplicate notifications being sent when the variant returns to stock.

Steps to reproduce

1. Register interest for a product using an email.
2. Attempt to register interest for a product but change the letter case for some characters in the email address.
3. Interest is logged rather than returning validation error.

Craft CMS version

4.13.2

Plugin version

3.0.3

Multi-site?

Yes

Additional context

DB driver is PostgreSQL 14