Why does HTML entities are still encoded in Code Block?

In the Code Block if I type in reversed character, they are encoded to HTML entities:

• Input:

• Output:

  pre class=wp-block-codecode'#91;] /code/pre
  

Meanwhile, if I put them in the custom HTML block, the output characters aren't encode:

• Input:

• Output:

  code'[]/code
  code class='[]/code
  codecode class='[]/code/code
  pre class=wp-block-codecode'[]/code/pre
  

I wonder why this should be the case? I enable troubleshooting mode and use the Twenty Twenty-One theme.

_{Related: Why does the custom HTML block not preserve the HTML characters?}