Has been is the present perfect tense of "to be".
The present perfect tense has a number of uses, but generally it is used to describe something that happened at one or more unspecified moments in the past and, more specifically, may be still continuing, or has the possibility of continuing in the present.
Note this description of the present perfect from englishpage.com: "We also use the present perfect to talk about several different actions which have occurred in the past at different times. Present perfect suggests the process is not complete and more actions are possible."
That seems to be the case with the sentence you are citing. It notes that Mr. Musk has criticized government policies since the pandemic started (implying that he did this one or more times). Since the pandemic is still going on today, this was obviously written during the pandemic, so the sentence also implies that he may be continuing to criticize government policies during the pandemic.
That pretty much sums up why someone would use the present perfect tense in this sentence. Having more context would help, but it's easy to imagine that this sentence may have followed a very recent quote from Mr. Musk in which he has just criticized government policies very near to the time that the article was written.
I hope that's helpful.