In many analysis of Ukraine's likely axis of attack, it often gets claimed that Ukraine will try to push on the southern region, to the Sea of Azov, next to Mariupol. Thus cutting Kherson/Crimea off from its land-bridge to the Donbas area and making a mess of logistics to Russia troops in the southern area.
So far, so good. What I don't get is the next step in these claims:
Ukraine will try to cut Crimea off, take out the strategically vital Kerch Strait Bridge that connects Russia with Crimea, and "just squeeze it over time make it untenable to hold."
Same claim from Anders Nielsen, a Danish military analyst @ YouTube, 8m:43 in (which I screenshotted below):
My question is: Given that the bridge in question was only completed in 2018-2019, how did Russia manage its logistics from/to Crimea from 2014 to 2018? What's different now? Did Ukraine allow passage to Russia goods on the mainland? Or is it because the requirements of wartime logistics are so much greater than supplying Crimea's 2 million civilians?