Strange rendering of diff code block

[mrdrivingduck]

When I try to render a diff code block in VuePress 2, the Markdown code and the expected appearance looks like:

-polar_hostid=1
+polar_hostid=2
-synchronous_standby_names='replica1'

However, when it is rendered by VuePress, the actual apperance looks like:

How does that come? I have tested on hljs and it seems to return right rendered format:

[meteorlxy]

We also use diff in our docs:

You'd better provide a reproduce repo.