Font formatting (BBCode) in RichTextLabel stops working when using theme type variation

[jedomed]

Tested versions

• v4.2.1.stable.official [b09f793]
• v4.2.2.stable.mono.official [15073af]

System information

Linux Mint 21.1

Issue description

I'm not sure if this is a bug or if I'm missing something. I have a RichTextLabel with BBCode enabled, when it's using the theme's overrides for RichTextLabel it works fine, but when I create a custom type from RichTextLabel then formatting stops working:

("default_color" is the only override)

(No overrides, just Base type = RichTextLabel)

If I manually create font resources and set them in the "bold_font", "italics_font", etc. overrides for the custom type then it works, but I shouldn't have to do that.

Steps to reproduce

1. Create RichTextLabel with BBCode enabled
2. Create Theme with a custom RichTextLabel variant
3. Set RichTextLabel to use variant
4. BBCode stops working (tags don't render, but no formatting happens)

Minimal reproduction project (MRP)

MRP_RTLVariant.zip