To clear up any misunderstandings, LB3 is scaled on the entire ilevel of your group. An LB3 with a full party of people in ilevel 530 gear will do more than LB3 at ilevel 510 gear.

Inside Bozja, everyone is ilevel 430, however bosses inside Bozja are scaled differently to other group content in the game, even at ilevel 430, a group of people with all their essences and skills will do more DPS than LB3 because you're doing more DPS than what is expected at ilevel 430. You can easily pull off 30k as a WHM inside Bozja at ilevel 430 because of the essences and Lost actions provided, with Bozjan content scaled around that instead.

Outside of Bozja however, content gets outpaced by newer gear, and sometimes LB3 might not even be possible to obtain, to use an example - Hades Normal is scaled at ilevel 420, but everyone is at ilevel 510-530 nowadays compared to ilevel 420, killing it with twice the amount of DPS and speed compared to the release of Shadowbringers where everyone had ilevel 430, making it impossible to obtain LB3 in Hades. But content released in 5.5 - such as Diamond Weapon, LB3 can do a considerable chunk to speed up a kill by 10 or 20 seconds, just 10 or 20 seconds is a massive gain to fights that have an enrage timer. Compared to Yohra however, Yohra's bosses have their HP 3x more inflated because there's 24 people in an instance vs 8, and LB3 only scales on your alliance party. If LB3 did 3% on Diamond Weapon, it'll do 1% on a Yohra boss because their health is 3x more inflated.

I hope this makes some sense. Tl;dr An LB3 on Diamond Weapon does 3% of his HP bar but 1% on a Yohra boss because of HP inflation, scaled on everyone's ilevel of your group.