HTML field (redactor) strips out commas from "tel:" links

[danbrellis]

Description

When saving a redactor field with a phone number that contains commas (,) it is parsed to remove those commas. This is problematic for conference call-in numbers that use the commas to 'pause' before dialing the dial-in passcode. This is ultimately a result of HTML Purifier and I have opened an issue with them: ezyang/htmlpurifier#388

However, just like Craft will sanitize svgs before running the purifier and then putting them back, I wonder if this is something Craft should handle?

See https://github.com/craftcms/html-field/blob/main/src/HtmlField.php#L198-L213

Alternatively, I would think a BEFORE_PURIFY and AFTER_PURIFY event pair would be practical here so I could santize those links myself. Other ideas or guidance is apperciated.

Steps to reproduce

1. Create a redactor field with 'purify html' enabled.
2. Create a hyperlink with the href of tel:+12029910477,,32288696#
3. Save and see how the href is now tel:+1202991047732288696# (no commas)

Additional info

• Craft version: Pro 4.5.6.1
• PHP version: 8.1
• Plugins & versions: craftcms/redactor (v3.0.4)