Sounds like a long-awaited race condition finally coalescing.
The boot splash screen would expect the drivers to be ready, and will hang/timeout if it isn’t ready when it tries to render the splash screen
“Recently there have been a number of reports about the plymouth boot splash not showing properly on PCs using AMD GPUs.
The problem without plymouth and AMD GPUs is that the amdgpu driver is a really really big driver, which easily takes up to 10 seconds to load on older PCs. The delay caused by this may cause plymouth to timeout while waiting for the GPU to be initialized, causing it to fallback to the 3 dot text-mode boot splash.”