Thanks for contacting Syncfusion Support.
We have validated this comma appearing issue in our latest version of 18.104.22.168 and as reported, we can able to reproduce it. But it is not an issue, since we have provided two-way binding for multiple values support in the Knockout JS that results in appending the delimiter character in model value. Hence, we request you to remove the delimiter at application level. Because on removing the character at end of key will create several usability issues. Like every time on search user need to manually enter delimiter character to resume search. So, it is recommended to remove the delimiter in your application level.
Please let us know if you need further clarifications.