What has happened to Foden

I have always been a firm believer that Foden was the best out of him, Saka, and Palmer. Especially after winning the POTS last season. I know he was injured beginning of the season and I thought the goals and assists would start coming but now it’s mid December and he still has 0 premier league goals which is genuinely insane to me. I don’t watch city games every week so I don’t really know why he’s underperforming so much. Is it a change of system? Low confidence? I thought he had an okay game today against Man United but he’s been nowhere near his usual self