I am not a tax professional but if it is was a rental, you'd be paying income tax in 2023. And I suspect the tax would be on the full amount (~30%) because the annual dues you pay are based on prorated calendar year and the same whether you take advantage of MB or not.
However, Disney refers to it as a "rebate" which, based on IRS publications, reduces your tax cost basis. This will impact your capital gain if/when you sell (you will have a bigger gain or smaller loss) but there would be no immediate tax consequences.
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Here is a link to IRS Pub 551 -
https://www.irs.gov/pub/irs-pdf/p551.pdf
The following is from page 5:
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If you accept that interpretation, then you did technically buy for $161 and just started usage of the property later. As I mentioned, I am not a tax advisor, but I do think there is a very good reason they call it a rebate and not a rental, and you can only do it at the time of purchase.