the way you describe what you have done, there is no federal limit or deduction or credit. everything is at the state level except the need to file a federal gift tax return since the amount exceeds the annual exclusion
see this link
https://www.savingforcollege.com/article/maximum-529-plan-contribution-limits-by-state
ohio allows up to a $4,000 year deduction (against ohio taxable income) each year. any excess contribution is carried forward. nowhere do i see $75K or %150K mentioned
there is a section in Turbotax under education for ESA and 529 QTP but that's only if
