Sorry but i don't understand what this post is doing here:

• it's not about privacy, as it's about subscribing to public posts on public forums (unless this is supposed to raise awareness about why multiple identities/nicknames is important?)
• there's not enough context to understand wtf is going on

I'm not privy to what is going on, who the users from the screenshot are, or what this is all in reference to, but saying they "actively setup RSS feeds" for this is a bit disingenuous. The ability to consume Reddit users' RSS feeds has existed for longer than GrapheneOS has been around. Anyone posting on Reddit (especially on public subs) or any other public site should have the expectation that their posts/comments can be monitored/tracked/followed, searched, recorded/copied, etc. This should just be viewed as a reminder of that.