There is an issue in edit mode with text wrapping. By default, the <pre><code></code></pre> element uses text-wrap-mode: nowrap; from prism.min.css.
Prism does not wrap the text, but the underlying textarea does, which results in a visual mismatch.
Example:
<MudCodeViewer @bind-Code="@code" Language="CodeLanguage.Razor" Editable="true" />
Even if you explicitly set Wrap="true" or Wrap="false", the issue still persists.
PS:
When toggling the editable state, the syntax highlighting is lost until the text is modified.
Example:
<MudCodeViewer @bind-Code="@code" Language="CodeLanguage.Razor" @bind-Editable="isEditable" />
PS 2:
When using show lines, there is also a mess.

There is an issue in edit mode with text wrapping. By default, the
<pre><code></code></pre>element uses text-wrap-mode: nowrap; from prism.min.css.Prism does not wrap the text, but the underlying textarea does, which results in a visual mismatch.
Example:
Even if you explicitly set Wrap="true" or Wrap="false", the issue still persists.
PS:
When toggling the editable state, the syntax highlighting is lost until the text is modified.
Example:
PS 2:
When using show lines, there is also a mess.