This is somewhat ambiguous because you stated your basis changed from 5 to 7 years. Actually, a change from 5 to 7 years would be a change in your recovery period (class life), not a change in your basis.
Regardless, you will probably have to post more information (e.g., where you are seeing this change, when you placed the assets in service, whether you changed anything else with respect to the assets).
There would have been no change to recovery periods as a result of tax reform for assets placed in service prior to the 2018 tax year (or, for certain assets, prior to September of 2017).