Copy an excerpted value from the last comment using two delimiters when a new comment is posted and update a field with it.
Create a new rule and name it appropriately.
Providing a description will help you to identify what the rule does but this step is optional.
Add a Trigger → Issue event → Issue Commented
No further configuration is needed.
Add a Condition → Boolean condition
Adjust the following expression to restrict the scope of the automation to the project of your choice.
Update field action
Next to the boolean condition, add an Action → Update field
For this use case, we will update the field Assignee.
Choose Value returned by parsed expression
Set the mode to Advanced text and enter the following Parser Expression
By replacing the texts "Assign to the user with " and " username" in the previous expression, you will be able to set different delimiters. The text between these delimiters will be copied.