their content (or a copy, if it keeps changing / moving), and you use non-inflammatory language to demonstrate the issue.
What you don't do is get into a name-calling match.
Here's the difference:
Wrong:
"e/OS developers are hawking insecure crap and we're oh so much better. And they insulted my mum!"
Right:
"GrapheneOS doesn't suffer from <link to info about a flaw in e/OS> - we've put a lot of effort into this, see <link to description of work> to get it right for users!"