@Xray2000 By the way, I've downloaded recovery from other source than your link earlier. That was recovery for Oxygen OS 4. But sha256sums of both images are the same.
So I don't know if I can trust this recovery and where I can get recovery for OxygenOS 9.0.6 available now.
Any suggestions?

@Xray2000 Thank You very much. Could you tell me how i can know for which version of stock image this recovery is, or whether it does metter? And maybe someone has exprience in returning to stock condition and can give me some advices and valid links.
I found a lot of outdated tutorials and broken links so l prefer to ask You help to be sure I'll be able to do everything right.
I will appreciate a lot.