"Contact is added to group" triggers by a change on contact's email signature

I have setup a rule to send an email, when a contact is added to a specific group. When I update the contact's signature of any email address of this contact, the email is sent.

Steps to reproduce:

1. Add rule "Contact is added to group" with linked condition "Group is" and action "Send email" using a mail template
2. Edit a contact subscribed to this group
3. Change the signature of any email in this contact

Expected behaviour:

• nothing happens

Actual behaviour:

• the email from the rule is sent

Environment:

• Wordpress
• CiviCRM 5.37.1 (I observed this error also several versions before)
• CiviRiles 2.23 (I observed this error also several versions before, I think I started using CiviRules with v2.19)