It's a botnet - was mostly operating out of Eastern Europe initally, but has spread everywhere now
That "no_matches" is apparently a security loophole in some plugin (not sure which one)
also see this thread https://wordpress.org/support/topic/multiple-failed-logins?replies=3#post-5818870
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mikeotgaar on "[Plugin: Wordfence Security] many failed login using an invalid username "no_matches""
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