You do have the option to turn that tracking pixel off in Admin if you would like to. What the tracking pixel does is when a user reads their email and it gets marked as "read", that sends an update to the ticket's "Read By" tab to show their name and the date and time they read the ticket. Turning the tracking pixel off will apply this to all notifications coming from that ticketing application. Other than no longer updating the "Read By" section of the ticket, it would not otherwise change anything, so it depends on whether you like that feature on the tickets.
To make the change, go to Admin>Ticketing Applications>[the ticketing app in question]>Notification Footers. Unless you have created additional footers, there will be only one listed here. Click Edit, un-check the box for including the tracking pixel, and hit Save.
I hope this has answered your question as well as informed you about what the tracking pixel does and what will happen if it is turned off. If you have any further questions, please let me know.