Stuck on Launcher Final Fantasy XIV Logo (MacOS)

In all likelihood it's because the game does not actually run on Intel Iris Pro graphics under MacOS. Technically it's always required a dedicated GPU as the listed minimum system requirements; it's just that previously, it would work on Intel Iris integrated graphics anyway. With the change to the setup the game needed to keep running after Catalina's 64-bit requirement landed, the Intel Iris support went poof; the game now used a DirectX -> DXVK -> MoltenVK translation pipeline for graphics, but DXVK requires Vulkan 1.1 to function for the game, and MoltenVK could only support Vulkan 1.0 on Intel Iris so far as I could see.

The 2018 MacBook Pro, so far as I recall, uses Intel Iris Pro graphics. If you have access to an external GPU (eGPU) supported by MacOS like the Sonnet eGFX Breakaway Puck 560 (Radeon 560), or the Blackmagic eGPU (Radeon 580), or the Gigabyte 580 Gaming Box, or even just grabbing an empty eGPU enclosure and stuffing an AMD card of some sort in there (MacOS no longer has current drivers for Nvidia), the game should work with that.

It's worth noting that while the Apple Silicon MacBook Pros (i.e., with the M1 ARM chips) do not (yet) support eGPUs, people have reported the graphics in there have enough oomph on their own that those laptops don't need an eGPU to run FFXIV with relatively decent (i.e. ~40fps) performance. (Which is actually pretty impressive, considering that to run FFXIV on an M1-based Mac you're running two graphics translation layers called through an OS translation layer on an emulated Intel chip.)