Loads of issues, majority of their features are completely missing and since nvidia are asshats that keep things proprietary a lot of it lacks equivalents that are of the same quality as their features.
The absolute biggest issue for me is Wayland support being complete crap on nvidia.
That’s not what’s going to happen. I really don’t understand why people on Lemmy are so fussed about this, Meta are not building a lemmy instance, they are building a twitter clone. While yes you can access Threads content through Lemmy that doesn’t mean it’s going to affect the Lemmy ecosystem. Mastodon is going to be way more affected than Lemmy ever will be.
Just because they are on the Fediverse doesn’t mean it will make sense to use their services through all other Fediverse platforms and vice versa. Following an entire Lemmy “sub” on threads will be a shitty experience and Threads doesn’t have creation of subs as an option, the only viable equivalent features are user posts.