I'll play devil's advocate. Let's look at some facts and the timeline.

Sync for Reddit has 1,000,000+ downloads, according to the Play Store listing as of writing. It has existed since ~2012 and is well established as one of the best Android reddit apps. To put that number into perspective, that's roughly one Sync user for every 2 posts on Lemmy (https://lemmy.world/post/2581495).

Liftoff is a brand new app created for Lemmy. Further, Lemmy itself is just becoming known. There aren't many people here.

Sync announces and releases the beta of Sync for Lemmy.

Everyone who has Sync for Reddit installed still gets a notification that Sync for Lemmy is available.

Sync for Lemmy becoming available means that many more people are about to sign up.

The topic of Sync for Lemmy, regardless of whether it's positive or negative, is at the top of Lemmy's "All" in multiple posts all week. That is happening on a lot of communities, this post on Liftoff being one of them. Naturally, people who enjoy sync are going to see these posts and will want to voice their opinion. Can you blame them?

I think it is disingenuous to assume malice in the sense that sync-stans are actively searching for negative Sync posts like you are claiming.

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Adding in my personal bias: I think the majority of the anti-Sync conversation is rooted in gatekeeping newcomers to the fediverse. Which is really, really unfortunate. But that's the kind of attitude that exists in online forums like this so that's what we'll get.

I am using Sync and will continue to. That's my personal choice. Everyone has their personal choice and that means others should fuck off about that choice. This goes for both sides, but I think it's more important for the anti-Sync crowd to hear because right now it seems like they are the ones who are truly up in arms about it all.