One other (labor-intensive) way to mitigate this lack of code highlighting for questions tagged system-verilog but not verilog would be to edit each question so that its code blocks are introduced with
```verilog (whatever highlighter tag verilog uses)
```lang-verilog (use verilog highlighter, regardless of the tag default highlighter)
instead of just ``...
As of 2020-09-24, all stack exchange sites use highlight.js for code-formatting and syntax-highlighting, see
Goodbye, Prettify. Hello highlight.js! Swapping out our Syntax Highlighter
The list of languages supported by highlight.js is at https://github.com/highlightjs/highlight.js/blob/main/SUPPORTED_LANGUAGES.md and verilog and VHDL are both on ...