I have not tested it, so it is just a guess: Maybe, you might have to add the “multiline” modifier to the regex, since your current syntax finds only certain characters between the start and the end of the string. Or, you might have to add the EOL characters “\n” and “\r” to the allowed list of characters. Or it might be, that you have add both Just try all three variants…
Thank you a lot for thinking about how to improve the regualr expression!
However, in the case of textarea fields in blueprints there seems to be no way to validate the input of users. In case of other field types you can validate the users input with given field properties (e.g. a number field with the property min or a text field with property pattern). The textarea field hasn’t got such properties.
(The consequence of the lack of input validation is that any user content has to be programmatically escaped when it is used as output in templates.)
The remaining question is, which possiblity are there to avoid malicious content in textarea fields within blueprints (before the content is published)?