About this:
It’s not clear how it failed. Failed to download the .iso file or what?
Also, I’m not really sure, but I think the Info: "Reading and/or parsing .zsync file failed!" is harmless and probably just means there’s no reference old .iso or partial download to resume.
(To be honest I’m just guessing here, I’ll check later)
About the writing to USB problem, could be a number of things, all I know is most people use Ventoy with success. And it gives two valuable benefits: you can still use the USB for other things, and in case of problems it’s easier to understand if you’re dealing with a corrupt .iso file or a corrupt USB stick.
There’s also another option that does not involve USBs at all and worked for me: Handy scripts you'd like to share - #44 by meanruse
It doesn’t hurt to have a bootable install media in a partition after all.
Where there’s a will there’s a way…
And, not to be rude, but there’s no point venting your frustration here like that, it’s not constructive.