Central bank monetary policy is to usually add a little bit of extra money supply because most central banks with a reasonable policy have determined that a low rate of inflation is better for the growth of an economy in the medium to long term than none, because it keeps a small upward pressure on demand and this extra entropic cost results in slightly better and perhaps more consistent growth (which is helpful for the economy as a whole). This was especially true when demand doesn't naturally drop due to change in long-term consumer behaviour but a short-term external event.

The corona crisis resulted in a sudden and huge deflationary trend as millions lost jobs, most people stayed home, and small businesses closed, creating a crash in demand. So they printed lots of money to help buck the deflationary trend as much as they could. And because you can print money, you can eventually slow down printing to let the economy catch back up once it has caught steam after deflationary trends are gone. So yes, it may cause latent spikes of inflation, but at least in this case it's good for the economy because that means more businesses are opening and more people are looking to buy things.

However, even after printing so much money, it is not clear if in the long term deflationary trends can be bucked. Japan has been trying for a long time, and Mario Draghi's 'whatever it takes' policy have led to negative interest rates for Euro bonds. And I already told you why deflation is not such a great thing for the economy as a whole. A currency with inbuilt deflation to me sounds like a very bad idea, because money in my account continues to gain value even though it is doing nothing productive.