Unfortunately all apps are suffering that issue because Lemmy doesn't support OAuth2. It's one of the many things on the dev backlog, but hopefully it won't be too long.
You need to supply the app with your username and password. The app could theoretically steal your credentials when you enter them in order to login. It’s a good reason to not reuse passwords.
I mean, maybe users are just excited about finding a place to land after the exodus, and an app that does feel very similar to Apollo.
I am using it based off seeing it mentioned a couple times and was very pleasantly surprised it’s similar to Apollo. Definitely makes the transition easier.