There has been an increase in the number of people asking for example sentences. There are more people around here than there has been in the past. There has been a problem with the network for many days.
“there have been” suggests plural whereas “there has been” indicates the singular.
There has been a critical error in this website There has been an error in Microsoft store There has been a decrease in human population There have been changes made by government. There has been a globalization of culture.