Open up the Instructions for Form 5695, then do a "search" for "heat pump" and you will find your answer.

https://www.irs.gov/instructions/i5695

In general, the share of new homes using an air or ground source heat pump as the primary means of providing heat has increased, going from 23 percent in 2000 to 40 percent in 2021.

Probably why Congress has decided it does not need to encourage their use -- although retrofitting an existing home might save energy costs.