The 34 year-old defender was released by Manchester City at the end of last season.
Debuchy told L’Equipe: “The situation of Sagna? I can not explain it to myself.
“He may be a victim of the policies of some clubs that prefer to rely on young people. Maybe he also has expectations on certain factors: the sports project, the family, the financial aspect.”
Sagna is currently in talks with Leicester City and West Brom.