
This is expected behavior in Customer Insights - Journeys.
The Email Link Clicked trigger can fire for any email click first, and then evaluates your condition (Email = Email1). If the click came from Email6, the contact enters the journey but immediately exits because the condition is not met.
To fix this:
If configured correctly, contacts who click links in Email6 may still briefly enter the trigger evaluation, but they should be filtered out immediately and not continue through the journey.