Any fights that need coordination from the DPS is going to be a tough matchup in the duty finder. Garuda has very specific mechanics that a lot of casuals just can't handle like "hide behind a pillar" and "kill feathers" or the toughest one, "kill the green tethered, or non-red tethered one first". Ifrit is fine because all you do is punch ifrit while the BLM/SMN limit breaks the nails, so there's not much to look out for other than the bright balls of flames under your feet. Garuda not so much.