Some of the states I've lived in with state income tax piggyback their state tax forms on the federal forms. Some added back in some money deducted on the 1040x, some added deductions. The state form instructions would say things like, "On line 2 of the state form, write in the amount on line 28 of federal form 1040, line 27 of federal form 1040A," etc.
Some were entirely independent. Even to the point of repeating most of the deductions. Either way, you got to very similar figures for the net income to be taxed.
This just uncouples the state taxes from the federal forms. Expect a lot of states that had them yoked to do likewise--not because some new tax cut is extended to their citizenry, but because the way the tax forms are written. Sounds like MD's tax laws were a bit too tightly coupled to the federal regulations.
(My first 5 or 6 tax returns were filed in MD; but my father did them for me since I was in college at the time and the returns were straightforward; the year I took over my tax return filings I had no income in the state of MD and didn't file a MD return. Probably wouldn't have remembered to do so if I had, actually.)