Same issue with other instances. I've switched to Voyager (wefwef.app) until Sync for Lemmy is released.

Yeah I've been getting that since the Lemmy update the other day.

Somewhat related... Why doesn't Firefox on Android support true PWAs?

Firefox keeps giving me reasons to not want to use it again.

At least pull to refresh is there now.

Hmm interesting. I never even tried to run Lemmy as a webapp. What's the advantage compared to using a mobile client?

Same here. It indeed seems to be with the installed versions of websites only. I use lemmy.ml