Well, I can see it. It really depends on what you think the multipliers for god forms are. I think that Autonomous Ultra Instinct-Omen's strength is equal to 2X SSBE, but it's fast enough to geth through Jiren's Defenses. And I think Mastered Ultra Instinct is 4X SSBE. The reason why I say this is when Vegeta in SSBE and Goku in SSB Kaioken X20 fought with Jiren, they actually had the ability to knock him back and send him through the kachin debris. I don't want to overpower UI, but I don't want to underpower it either. So I'll give a personal scale of my own.
Super Saiyan god (according to in series and author's notes and interviews) should be around 6X SSJ3. Due to how most people think that SSJ Grade 4 is still 50X and SSJ2 is 100X, I will put SSJ3 a 400X. So I will put SSG at 2400X
Super Saiyan god = 2400X
god-like saiyan = (depending on mastery, anywhere between 0X-2400X)
Super saiyan Blue = 50X whatever your god-like saiyan mastery allows. At most, maybe 50X SSG (At most 120,000. At Least 2400X. generally through the series 19,200 (courtesy of FlatZone) )
Super Saiyan Blue Kaioken = 120,000 X 20 = 2,400,000X(Kaioken requires perfect ki control to use with Super Saiyan)
SSBE (equal to SSB Kaioken X20) = 2,400,000X
Ultra Instinct Sign = 4,800,000X
Mastered Ultra Instinct = 9,600,000X
This is assuming that Jiren was at least using 50% power against Goku and Vegeta.
As much as we'd like to assume on how much power Jiren was using, he didn't use his full power until he powered up and tried to attack UI Goku with that Giant Energy bomb which Goku caught and then dispersed, Jiren proceeded to get overpowered at his full power, until he awakened his Burning Ultimate Warrior state and was even with UI Goku again for awhile
I suppose we don't know how much power he was using. But if he was even using 1% against Vegeta when Vegeta got his lucky kick, then against SSBE Vegeta and SSB KKX20 Goku, he would have had to use at least 40% to stay ahead. So, if 50% or Jiren was equal to UI-O Goku, then 100% Jiren would be equal to MUI Goku. I was counting his Burning Ultimate Warrior as a part of his 100%.