...and why would Goku, Vegeta and 17 suddenly be so much more powerful that it would warrant Jiren needing to power up? Goku and 17 have no impetus or indication of it. Only Vegeta would have grown any stronger (his power being stated to rise against Toppo) but this is contradicted by Vegeta nearly dying from Final Explosion and being knocked out of SSBE, when Goku wasn't knocked out of SSB.
In the video you link, Jiren even specifically notes Vegeta is wounded. 17, who spent the entire fight against Toppo focusing on evasion and unable to do a damned thing, felt the need to even block an attack for SSBE Vegeta. 17 even intercepted Jiren's blow, that Vegeta couldn't properly react to, from a further distance.
Jiren was even fighting SSB Goku and 17 at the same time that SSBE Vegeta was fighting him, he didn't even show any surprise or difficulty until Goku approached him from behind, and he easily knocked SSBE Vegeta away to deal with Goku, who went KK.
If you pay even the slightest hint of attention in the fight, it's blatant that SSBE Vegeta was constantly on the losing end of the fight, that 17 felt compelled to intercept and block blows for Vegeta and that KK Goku Blue was pushing and fighting Jiren much harder than Vegeta was.
The only hint of respect or surprise Jiren displays towards Vegeta's strength, was him stating he 'I can see why you were able to defeat Toppo' and that's it.
Ultimately, 17 and Goku were far more impressive than Vegeta against the powered up Jiren, have way better feats and didn't have their wounds or power drain be explicitly stated as a concern in-universe in the context of this fight.
Now, I'm not claiming for a second that KK Goku Blue is SUDDENLY stronger than SSBE Vegeta or that 17 should scale anywhere close to Post-UIS2 Goku and SSBE Vegeta. Fact of the matter is, Vegeta was heavily drained and injured and this fight was filled to the brim with absurd outliers.