The Soviet system used psychiatry as a weapon by diagnosing political opponents as mentally ill in order to confine them as patients instead of trying them in court. Anyone who challenged the state such as dissidents, writers, would-be emigrants, religious believers, or human rights activists could be branded with fabricated disorders like sluggish schizophrenia. This turned normal political disagreement into supposed medical pathology and allowed the state to present dissent as insanity.
Once labeled in this way, people were placed in psychiatric hospitals where they could be held for long periods without legal protections. Harsh treatments were often used to break their resolve. The collaboration between state security organs and compliant psychiatrists created a system where political imprisonment was disguised as medical care, letting the Soviet regime suppress opposition while pretending it was addressing illness rather than silencing critics.



From the article, western sources claim some 15k people affected over the entirety of the Soviet Union. So yeah, something that did happen, but still quite a minor thing for a country with 300 million people over 70+ years of existence.
For comparison, over 700k people experience homelessness today in the USA, which is arguably at least as damaging to mental (let alone physical health), and if we count the number of people who have experienced homelessness over the past 70 years in the USA it’s several million if not tens of millions.
not to mention that 700k number is highly underestimated
according some studies, real numbers maybe 5 to 6 times of that https://abcnews.go.com/US/accurate-annual-count-us-homeless-population-misses-large/story?id=106671876