6.1 Beta no longer allows SVG in custom block dynamic rendering

[robglidden]

Testing Instructions

Steps to Reproduce

1. In WP 6.0, create a custom block with dynamic HTML rendering
2. In the 'render_callback' php function, return an SVG as part of the returned content.
3. The SVG renders on the front end as expected.
4. Switch to WP 6.1 with the beta tester plugin.
5. 🐞 The SVG disappears on the front end. It is stripped from the HTML>

I imagine that there is some new escaping on the HTML returned from the 'render_callback' function.

However, there needs to be some way to insert an SVG in a dynamic PHP-rendered custom block.

I also notice the same stripping of SVG occurs when I use the new block.json render feature ("render": "file:./render.php").

[robglidden]

For whatever reason, this is now working properly in 6.1 Beta 2