From the above link, it looks like the fix has been released in twebengine-opensource-src - 5.15.5+dfsg-2.
Waiting for things to be back to normal the following trick, make it works:
$ export QTWEBENGINE_CHROMIUM_FLAGS="--no-sandbox"
$ insync start
$ export QTWEBENGINE_CHROMIUM_FLAGS="–no-sandbox"
$ insync start.
Working on Budgie 21.10
Thanks
We use the one installed by the system as far as my knowledge on this topic goes but let me clarify that with our engineers and will get back to you!
Thank you so much for sending the fix to let things run again - I’ll send this to our Linux team so we can follow suite 
This also solves the issue on OpenSuSE Tumbleweed.
This also solves the issue on Fedora 35 KDE Beta.
Just for completeness sake, this solves the issue for Fedora 35/Gnome 41 as well.
Works on Kubuntu 21.10 ! ; To avoid restarting at each reboot :
1 - Create .sh with :
#!/bin/bash
export QTWEBENGINE_CHROMIUM_FLAGS="–no-sandbox"
insync start
2- Edit launch application command Insync and browse to the .sh location.
This launches the program normally while waiting for the official patch
this does not solve the problem for me. Tumbleweed and insync 3.5.4.50130-fc34. After the export command nothing has changed and the app window is still blank.
any news for ubuntu 21.10 ???
The workaround is sort-of working for me on Ubuntu 21.10, in that the UI is now being displayed - but there’s no title bars (so you can’t move the window…) and there’s no tray icon.
Hey @cmannett85, thanks for letting me know the workaround works except for the title bars and tray icon. I’ve responded to the thread here re: startup and UI issues
Hi! Can you send your logs.db and out.txt files to support@insynchq.com? Should be in ~/.config/Insync.
Tried the workaround and it did not work. I’m in fedora 35 gnome 41
Same here. Fedora 35, Gnome 41, Wayland session. Besides this, the app works fine, syncing the files.
Hi all! My apologies for the wait, and thank you for your patience!
Our engineer has updated our Linux repositories and builds with the following additions:
Please update your packages and do let me know on this thread (or by emailing support@insynchq.com) if any issues persist!
Had the same issue on Opensuse Tumbleweed. Fixed by uninstalling and reinstalling Insync, logging in again, everything working again. Just FYI
