I have seen this around the Internet and a lot of the information is old, and incorrect at the date of this blog post. Thus, what I will link here is the official support matrix Cisco provides for the Cisco Nexus 9000 series switches and the support Cisco Nexus FEX models. One thing to note, if you hover over the “YES” in the cell you choose, it will provide you with the supported connectivity options.
Now, to answer the question above, yes, you can connect the Cisco Nexus 2348UPQ to the Cisco Nexus 93180YC-EX using 40GbE from the FEX uplink ports to the 40GbE ports on the 93180YC-EX. If you are reading the guidelines and limitations where it states something like this “FEX is not supported on 40GbE ALE uplinks” then you need to understand the Cisco Nexus 93180YC-EX does not use the older generation ALE, instead it uses the newer, 2nd generation, Cloud Scale ASIC LSE (Leaf-and-Spine Engine); thus, this limitation does not apply.