They've been replaced by the PSS silent pistol. It's a bit louder because of the moving slide, but still quite silent. Notice the racking of the slide at 0:19 and compare with sound of firing the gun, it's the same.
OTs-38 are no longer produced but some are still kept in service because there is a supply of ammunition ready, and because the revolver doesn't leave behind any casings.
Pretty sure we can't buy it in America, considering all the sanctions and import bans.
