Syntax highlighting for XML broken for Authors

[eugenschindler]

When an author makes a syntax highlighter block and sets it to XML/XHTML/... then the highlighting is completely broken and even the text is not displayed properly.
If I set the same user to editor instead of author, the highlighting suddenly works.

I didn't check other languages than XML, but they may have the same problem.

Using WordPress 5.4.

[alexsanford]

I can reproduce this for XML. For example, when I add the following code to a SyntaxHighlighter Code block in the Block Editor as an author:

<something />
<another />

Then I see this on the frontend:

When I change the user's role to Editor, and then change the block and save it, I see the following on the frontend:

[donnapep]

This was fixed by #160.