The English centre-back started excellently at the San Siro club in January, but has since made some individual errors.
Tomori's recent errors mean the club may move on from him when the season concludes, unless he is available for a knockdown fee.
Another loan to Milan or a different team next term may be a possibility, as there does not appear to be any place for Tomori in the Chelsea first team.
However, there is also suspicion the leak from the Milan camp could be a ploy as they want Chelsea to lower their transfer demands for the 23-year-old.
The Blues want Milan to honour the purchase they included in his loan deal, which currently stands at £26m.
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