Review and Complete | Decline to sign > Comments section accepting special characters

Pre-requisites :
1) Template should be created
2) User should send the form

Replication steps :
1) Email triggers on sending form
2) Click on Email link of "Review and complete"
3) click on Review and sign
4) Navigate to Decline to sign -> Insert special characters in comments sections
5) Decline Message sent successfully message shown

Expected Result :
System should show validation if special characters is inserted

PFA :