The youngster signed for City from Fulham in 2015 for a significant fee, nearly £12 million.
But he has only played a handful of games, and has a contract until 2022.
Middlesbrough are another club with an interest, as he was on loan there from January.
Unfortunately, that loan spell was cut short due to injury, but the club were still impressed with his talent.
Roberts is a winger who was on loan at Celtic for three seasons from 2016-2018, scoring 18 goals in 79 games.
The 23-year-old would be welcome there on a permanent basis, as he is popular among the fans as well.