Territorial scope of European Convention on Human Rights Wikipedia article does not include Belarus.
Human rights issues are confirmed by multiple articles such as this one:
The government continued to refuse to accept the mandate of the UN Special Rapporteur on human rights in Belarus. Several individuals seeking international protection were returned to countries where they were at risk of torture and other ill-treatment. Heavy legislative restrictions on media, NGOs, political parties and public assemblies remained in place. One person was executed and four were sentenced to death.
Coming back to European Convention on Human Rights country list, I see that many, if not almost all Post-Soviet states (e.g. Armenia, Azerbaijan, Estonia, Georgia, Russia) have ratified several or all the protocols (some exceptions may occur) from the Convention.
So, being a Post-Soviet state does not seem to be an important factor when ratifying ECHR protocols.
Question: Why does Belarus not seem to have ratified any protocol from European Convention on Human Rights?