Steps to reproduce the issue

While logged in as a Super User:

In the Global Configuration, set the Default Editor to Editor - None.

In the Text Filters tab, set the Filter Type value to Default BlackList for the Super User group.

Save.

Go to Content -> Articles -> Add New Article.

Give the new article a Title, and add the following HTML, or a variation of it, to the Content field:

<p data-value="1">Some text</p>

Click the Save button.

Expected result

The article should be save with the original content added intact.

Actual result

The hyphen is removed from the data attribute, resulting in

<p datavalue="1">Some text</p>

System information (as much as possible)

Joomla 3.8.8

Additional comments

This issue was introduced in the Joomla 3.8.8 update via commit cf4c5df with the inclusion of line 867 in libraries/vendor/joomla/filter/src/InputFilter.php

This line should be amended to allow for the - character, eg:

$attrSubSet[0] = preg_replace('/[^\p{L}\p{N}\-\s]/u', '', $attrSubSet[0]);