Same error - KUbuntu 22.04 + Dell XPS 9510
The workaround is to remove libstdc++.so.6:
sudo mv /usr/lib/insync/./libstdc++.so.6 /usr/lib/insync/./libstdc++.so.6.bak
Insync starts and seems to be working fine. @mia - I hope this helps
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