If you describe something as banal, you do not like it because...

Hi,

banal
If you describe something as banal, you do not like it because you think that it is so ordinary that it is not at all effective or interesting.
Example: Bland, banal music tinkled discreetly from hidden loudspeakers.
[Collins COBUILD Dictionary]

Doesn't a comma or semicolon need to be used after ordinary? This would read then:
If you describe... that it is so ordinary,/; that it is not at all effective or interesting. No, don't use this extra punctuation.

'That ' relates to ordinary. Consider a simpler example, eg 'She was so sick that she died.' It's all one related thought.

What does the discreetly mean in the quoted example? A mix of quietly, tactfully, politely.

Best wishes, Clive