I am receiving the same error as @John_Apple_II.
I am using a Fedora Silverblue based distro (Aurora). Obviously, it is not possible to install Insync directly onto an ostree based system, but I have put your repo in and layered Insync on top.
Two things. First I hope you can get your repo issue sorted out very quickly as this undoubtedly affects a LOT of users.
Second, I would like to do my best to implore the Insync developers to develop a Flatpak version of Insync as has been talked to death on this thread. I implore you to do this for so many reasons. In addition to the reasons listed on the previously mentioned thread, this repo problem means that my entire system is broken for moment, because when the Insync repo will not update, the entire system will not update. This is just one of the many issues that would not exist if there were a Flatpak version of Insync.
Thank you.
EDIT
This thread indicates that this affects more than just Fedora/Red Hat users. SUSE people are affected as well.