If someone was blocked me on Viber and then I get unblocked, is it because he unblocked me or he reinstalled the app? Are blocked contacts on Viber get unblocked by themselves when the person deinstall without deactivate & then reinstall the app?
No, blocked contacts on Viber do not get automatically unblocked when the person reinstalled the app without deactivating their account. If you were unblocked, it is likely because the person who blocked you manually unblocked you.