Maybe the research Ransomware attacks have decreased in the midst of emergency COVID-19 because hackers also have a personal life and are affected by this pandemic as well. But maybe only temporary. Currently there are many new methods that they use (hackers) to infect other people's devices using ransomware.
The number of useful ransomware attacks saw a reduction among January and April 2020 in the U.S. open segment amid the COVID-19 emergency.
I don't understand what you mean by useful ransomware attacks. Every attacks is has a malicious intent. On the contrary, I personally believed that with the COVID-19 the attacks has growing because cyber criminals are taking advantage of this situation as well. With so many COVID-19 themes attacks specially around March-April. And criminals are not going to take a rest so I would say that I disagree that the numbers or ransomware attacks are declining.
Attacks can indeed increase, in many ways that can be done. Criminals will indeed take advantage of this situation very well, because most people when spending time at home surfing the virtual world, attacks will continue.
For example, the new Ransaomware that appeared in Italy is amended to be a covid map that will affect users of the fake covid-19 map application. This is the thread that you created in May.
https://bitcointalk.org/index.php?topic=5251450.0Are People finally understand basic computer secuirty?
People who really give priority to security must know how to protect their devices from various viruses that can infect at any time. Basic security needs to be learned.
Safety is the main thing to think about, before surfing in cyberspace.