Tangential: as an experiment, I posted the same OP photo, the aerial of the flag on the "A" on my infrequently used Instagram account. As of just now: Mastodon: 87 shares, 88 likes. Instagram: 10 likes.
Granted, I have half as many followers there and haven't been following new people for quite a long time and don't engage much there, but corporate slop aside, that's one of the reasons. If you're not willing to aggressively attention-farm the algorithm, you don't exist.
Edit: 32 hours after OP:
Instagram: 14 likes, 1 share, 1 troll.
Mastodon: 112 likes, 105 shares, some nice comments by actual people.