Qualified Dependant

I am divorced and have two children.  Per my divorce decree I claim one and my ex-husband has claimed the other.

 

However, the child that my ex-husband has been claiming turned 18 in 2020 and has also lived with me consecutively for the last 2 years.  The other child has also lived with me consecutively for the past 12 months.

 

With the fact that the child that my ex-husband has claimed turned 18 in 2020 can I instead claim that child without consequence from the IRS?