I love how 137MB can be considered a reasonable size for a social media application. Because fuck users; what's important is the convenience of the developer.
I'm sorry but Flutter is not a thing you should ever develop anything on. Dart is a dead language that has no business continuing to exist.
That 137MB is for Lazurite. FluffyChat, also written in Flutter, is similarly bloated. Tusky, meanwhile, is 21MB.
I'd actually rather people didn't publish these apps, because then the niche would be left open and would be more likely to be filled by developers who don't think their users' computing resources are theirs to waste.
Flutter is a conspiracy by Google to sell higher-end phones by making apps bloated and slow.
What blows my mind is that Lazurite isn't even meant as a crossplatform app. If you're only shipping for Android, use Java or Kotlin or something. If you can't learn a new language, you're probably not very good with the ones you think you know either. Go touch grass.