@hrefna I think they just repurposed Instagram's backend, or perhaps even run it on the same backend with just a different client.

Some evidence: https://matrix.to/#/!uHqAjmOtrLtidOiczC:matrix.org/$UpSel-3jVGYrRSGz7D3MgkQDc9lFTD9XDrxEeaFrqk4?via=matrix.org&via=mozilla.org&via=exozy.me