MICRO-INFLUENCER of micro, Greek prefix meaning small and INFLUENCER, anglicism to name people who having a level of credibility on some issues, are followed on social networks, and promote brands and trends among their fans.
I suppose it's an English word, not only because 'influencer' is in English but also because of the script, which would not be used in Spanish. micro- ( "small, minor" ) is a prefix of Greek used in our language.