Reading the yaml documentation in https://symfony.com/doc/current/components/yaml.html#numeric-literals we can see the following code block:

Here, the numbers are all formatted as strings, except for the 3. for the parameters.pi property.

The correct rendering should be:

This may be a highlightjs issue (it looks like this project is using this library).

Libraries:

• I read an article about https://github.com/tempestphp/highlight, but I doubt the idea would be to change the library.
• I came across https://shiki.style/ while doing some research, it correctly highlight parameters.pi, but highlight the other properties as "string"