Came from 29.12.20 - umi + littleturtle twrp (we all know the fastboot boot problems and like impatience can be a problem here , haha) been there done that
1. backup (not with twrp) - just safed everthing on pc
2. got newest twrp from MB - big kudos there
3. booted to recovery (littleturtle)
Thats unfortunately i dont know - its the twrp 3.4.2 from LR.team - but its says in twrp at the end aso ..twrp 3.4.2 ...github1111. cant remember exactly.
but thx for the advice that i have to wait - i think its the impatience that it got me always back to fastboot.
i had the same issue. went from latest weekly miui12.3 - android 10 - to softbrick.
I used the miflashtool v2 - and stuck on the same error
flashing a new recovery worked, but it didnt boot - just stuck on fastboot.
ill try different twrps and somehow magically on my last try it...