Alberto Martín a researcher in bibliometrics and Google Scholar also notes that Google Scholar was the only major citation index provider who declined to respond to QSS's (a important journal on bibliometrics) invite to contribute to a special issue on data sources in 2020. While represenatives from Web of Science, Scopus, Dimensions, Microsoft Academic, Crossref and OpenCitations all responded. https://twitter.com/albertomartin/status/1314861003864182784