ALL the TX income is taxed as Ohio income, since you are an Ohio resident.
Normally, Ohio would let you take a tax credit for the taxes you paid to the "other" state, but since TX doesn't tax income, then Ohio taxes it all.
All other states with an income tax would do the same thing, so that is not unusual behavior.
If the employer withheld OH taxes, even while you worked in TX, then that is a good thing, since if they hadn't, you might now owe OH a few thousand in unpaid OH taxes.