Comma is not allowed to be part of Summary field while REST API issue create

“summary”:“Testing , 123”,

throws an error like below:
“Field Summary with actual value ‘Testing , 123’ does not match regular expression ^[A-Za-z0-9 ]+$”

Any possible way to escape , and similar characters : \ …

This kind of error message is returned by a regular expression workflow validator. It must be configured on your issue create transition to validate the summary field value.