MI DoT hasn't officially posted any update on the website.  If you believe the Detroit Free Press (https://www.freep.com/story/money/personal-finance/susan-tompor/2021/03/19/michigan-new-tax-deadline...), they quoted a DoT spokesman, saying that the exclusion will flow through to MI-1040 since it starts with federal AGI.

According to Michigan Compiled Law Section 206.607(6), the conformity date is still January 1, 2018.  That was updated back in Feb 2018.  However, that same subsection provides taxpayers an option to use the IRC "in effect for the tax year."  On that basis, unless the legislature passes a law to require an add-back for UCE, I'm inclined to believe the Detroit Free Press report is correct from a technical standpoint.

In case you're interested in a different perspective, here's a discussion from a couple days ago: https://proconnect.intuit.com/community/proseries-tax-discussions/discussion/is-the-state-of-michiga...