I'm not into FB/IG, but I'm curious why this was launched as 'an Instagram App', rather than 'by Facebook' or 'by Meta' or something similar?
The public associates Facebook/Meta with excessive data collection, overhyped VR, intrusive tracking, etc. That association is much weaker with Instagram.
On Facebook your experience is mainly your grandmother trying to write messages to you by typing them into any random thread or text box she sees.
Also it uses the Instagram infrastructure e.g. auth and design language.
Joking aside, this is a branding decision.