There's an on-going Reddit post about this as well, seems a bunch of people are getting their interview location switched, myself included:
Original poster of this thread had their location randomly changed from Bratislava to Frankfurt - and was told 'US Visa operations are being closed and case location automatically switched'.
@LangelBeanI also received the same mail as well for my wife who lives in AMSTERDAM with me currently, our interview location set as Amsterdam and randomly my case was switched to Frankfurt with no warning. I have just now sent NVC a public inquiry asking if this was a system error, or if US Embassy Amsterdam really are suspending Visa Operations. Either way, my newly assigned Frankfurt Case ID doesn't even work to log in.
@sweetspirit69 Perhaps yours is a bit different than this - maybe in your case, KYIV is re-opening operations again, and the NVC thinks because your spouse is Ukranian (Foreign State of Chargability) that they should 'automatically reassign them there'. As you can see from my examples, people are having their cases actually assigned TO Frankfurt Germany. Perhaps, if you can send NVC a public inquiry with an attachment proving that your spouse lives legally in Germany now (do they have a German Resident permit?? 'aufenthaltstitel' in German)? If your spouse has a German resident permit now, you can probably get the interview location switched back to Frankfurt. Worth a shot.