How could Vegeta defeat Hakaishin Toppo so easily? In the previous episode God of Destruction Toppo absolutely destroyed Golden Frieza (who is supposed to be as powerful as Super Saiyan Blue) and Android 17. His Hakai was also much more powerful compared to the Sidra's Hakai. Goku even with SSB Kaioken struggled against Sidra's Hakai ball whereas Frieza could easily control it. So Golden Frieza just before the Tournament of Power can be considered as strong as SSB Goku.

Also Vegeta's new found power is not as strong as UI Goku because UI Goku could go toe-to-toe and even gain up on Jiren. So if Vegeta's new found power is considered close to or slightly greater than SSB Kaioken then how did Vegeta manage to defeat Toppo in the very next episode so easily?
There are a few inaccuracies in your question.Firstly, Goku was in his base form when Freiza hit him with the Hakai energy and he didn't turn SSJB or Kaioken. In episode 125, we see the Destruction energy capable of destroying all forms of energy, so it is very likely Goku couldn't turn SSJB while he was stuck inside the energy ball. Freiza, on the other hand, was in his golden form and strong enough to break out of it.Based on the fight after, we see SSJB Goku per tournament was on the same level as Golden Freiza. It has to be noted that Goku in his SSJB from grew substantially stronger because of multiple Zenkai boosts.UI Goku was fighting against a very suppressed Jiren. UI Goku against Kefla was a lot stronger and she was strong enough to take blows from him(Which remarked by Whis weren't powerful as Goku hadn't mastered the attack portion of UI yet). Current Jiren is using a lot more power than he did then.Vegeta's new form before his fight with Toppo, was relative in power to SSJB+Kaioken*20 Goku(The stronger SSJB Goku), hence making him a lot stronger than Golden Freiza. Freiza in his golden form is even weaker than characters like Anilaza and Kefla in terms of strength. Toppo in his God of destruction form, was stronger than Kefla who was at that time the third strongest(With 1 being Jiren and 2 being Goku). This is why we see Vegeta overwhelmed by Toppo during the initial stage of his fight. When Vegeta powered up after, he reached a level of strength a lot stronger than Kefla and Toppo but weaker than UI Goku and hence was able to knock out Toppo.During the fight between Universe 7 vs Anilaza(We see 3 SSJB tier characters (And let us assume Gohan and Android 17 are even SSJB tier which they definitely aren't), so 5 SSJB characters being able to hold their own in a beam struggle with Anilaza. Kaioken * 20 SSJB Goku is the same power multiplied 20 times and UI Goku is immensely stronger compared to Kaioken Goku. Vegeta's form is relative to this(initially) and he was a lot stronger than Freiza when he first fought Toppo which is why he wasn't completely Toyed around with.