@optiso Wrong.
1- The manga is currently following the web comic almost perfectly. Everything that happened in this chapter (and the last few chapters) was from the web comic, safe for a few details and for the cat monster since that one is original to the manga. The only other detail is that puripuri prisoner didn't fight Garou in the web comic at this point in the story, instead it was only Darkshine who found him rather than Darkshine taking over the task of fighting Garou from puripuri. However, overall, it's mostly identical to the web comic, just with better art.
2- You underestimate Fubuki. She may be completely outclassed by Saitama, but everyone is. You can't evaluate her worth by comparing her to Saitama and Tatsumaki, nor can you evaluate it based on her Hero rank. When a Hero is the rank 1 of a class, they can move up to the next class at any time.
Mumen Rider stays C-Class rank 1 because he doesn't think himself to be strong enough to make much higher and because he wants to continue having the condition of being kicked out of the Association if he doesn't maintain a hero quote per month.
Sweet Mask stays A-Class rank 1 (even though he's actually stronger than most S-Class heroes) because he doesn't want to allow more weak people(from A-Class) to move up to S-Class.
Fubuki also has a reason why she doesn't rise up in ranks. Fubuki stays B-Class rank 1 because she wants to the best in at least one place, and she knows that she can't surpass overpowered people like Tatsumaki and Sweet Mask. She thus stays B-Class rank 1 because she knows she can't become A-Class rank 1 as long as Sweet Mask is there. However, if she actually chose to move up to A-Class, she'd most certainly quickly end up as A-Class rank 2. She's not weak by any means. Heck, in terms of powerSweet Mask she's certainly stronger than some S-Class, such as Tank-Top Master, Genos when he entered S-Class(though he's a lot stronger now) and Puri Puri Prisoner during the Sea King arc(though he might be stronger now).
Sure, she's not top S-class in terms of power, but that doesn't mean she's weak. Then there's also the matter of compatibility. Bang and Bomb(Bang's brother), while both incredibly powerful, likely wouldn't have been able to fight Rover due to battle compatibility. Sure, they might have not actually been disintegrated (since Bang has been shown capable of enduring a lot more than most can without much injury, as shown in the Boros arc), but they would've likely still be quite injured.
Also, Rover isn't weak right now. By that I mean that even if he's physically not able to endure as much damage as he could before encountering Saitama, that still has nothing to dob with the power of his breath attack.