Manchester City are certainly very happy to hear this news and hope that Mohammed Salah will be absent for quite a long time. They can more easily take advantage of Liverpool's current situation and at any time can displace Liverpool at the top of the standings. De Bruyne's return is an improvement in performance for Manchester City and the absence of Mohammed Salah will be a disaster for Liverpool.
Salah's predicted injury is a hamstring injury. I think it won't be too serious. In the short term, the Egyptian team will be directly affected if Salah is absent. As for Liverpool, their schedule this January is not too heavy, they only have to play one match in the Premier League against Bournemouth.
That's why Liverpool can completely give Salah the right to rest in the next few weeks if he is unfortunately injured. The Premier League championship race still has a long way to go. This is just a temporary shortfall for Liverpool. Mancity should not be too hasty to rejoice and lose focus.