Manchester City has marked an aggregate of 24 players while Pep Guardiola has been in control. Manchester United may be about to sign a Championship player but Manchester City has not been interested in that market under Pep Guardiola. Their preference for recruiting from other leagues predates the current manager; you have to go back to the purchase of Patrick Roberts from Fulham in 2015 for the last time the Blues bought from the second tier of English football, and the 2010 arrival of Adam Johnson from Middlesbrough for the last time they brought in a first-team player from the league.
Guardiola, though, has followed the trend. City has signed 24 players to date since 2016 and not one of them has come from the Championship, although John Stones, Kyle Walker, and Riyad Mahrez have all come from Premier League clubs. The only club that has signed more players from in Guardiola’s time in Spain. Claudio Bravo, Nolito, Geronimo Rulli, and Pablo Mari all arrived in 2016 (with the latter two immediately loaned back out), and Aymeric Laporte followed in January 2018.