For example,
Cell says he has the power to blow away a solar system with his Kamehameha. Meanwhile, Broly destroys 1/4 of the galaxy in his suppressed state. In comparison, our own galaxy, there is 3,916 solar systems. Divide by 4 = 979 solar systems destroy by Broly while in his restrained state vs 1 solar system by Cell at full power. This feat alone puts suppressed Broly as stronger than Cell at full power by a huge amount.
Perfect Cell tanked a kick to the head from Vegeta while suppressed. Broly also tanked a kick to the head while suppressed. How big do you think the difference was between Initial Perfect Cell and full power Cell Games Cell is? 5, 10, 20x stronger? FPSS Goku was around 2x CG Vegeta and Full power Perfect Cell scared Goku and Co so he was probably over 2x stronger than Goku was or more. Meaning that Full Power Cell was 4 or more times stronger than Vegeta. With room for a bit more. You could high ball and say 10 or even 20 times stronger.
Suppressed Broly still had super saiyan to use, 50x more power, then the Legendary SS to power up as well. Even if we lowball Broly's LSS transformation to as small as 2-3x multiplier, this puts him at least 100-150x stronger than Vegeta at the minimum. With room for insanely more. The LSS multiplier is more but I will use this smaller number for the sake of this argument.
You also have Cell taking a full power Kamehameha to the face and getting his entire upper body blown off. Goku tried the same thing with Broly dead in his face and Broly didn't even flinch.