I'm not disagreeing with Low 2-C ratings; especially for Cell Max, Orange Piccolo, Gohan Beast, and Gamma 2's final attack, but I feel as if directly comparing them to how strong Broly was at his peak is rather iffy until we see further demonstration. Goku, Vegeta, and Broly should still be Low 2-C even in the base forms at this point for sure; given Goku already has hints of a Low 2-C base form back in the Broly movie via initially matching Wrath state Broly who stomped SSB Vegeta right off the bat. Vegeta eventually trained and surpassed base Goku even in his own base form after learning some degree of Ultra Instinct. Broly is also implied to have gotten much stronger even in his relaxed state via sparring with Goku and was able to keep up and grow from watching Goku and Vegeta fight and meditating.
There's even a vague statement from Goku that implies his strongest forms have gotten stronger to the point where he doubts Beerus or Whis could stop his wrath state. He should definitely be stronger than Beerus at his peak, though Whis comparisons are questionable.
Though, Piccolo has some doubts of Goku and Vegeta putting a stop to Cell Max even if they were there despite being the one who teaches them Fusion Dance and knowing how strong SSB's are, but he may not be aware of how much they grew. But it should minimum be above ToP era SSB's which are within the Low 2-C ball park.