4.18.0-240.22.1.el8_3.x86_64 Sound works as expected.

4.18.0-305.3.1.el8.x86_64 only "dummy output" shows up under the Sound Preferences on the desktop.

I guess there's a kernel bug somewhere that's causing the driver for that soundcard to not load?

The lshw command (when running kernel subversion 240.22.1, i.e. the "old kernel") tells me that it has this soundcard:

*-multimedia description: Multimedia audio controller product: Sunrise Point-LP HD Audio vendor: Intel Corporation physical id: 1f.3 bus info: pci@0000:00:1f.3 logical name: card0 logical name: /dev/snd/controlC0 logical name: /dev/snd/hwC0D0 logical name: /dev/snd/hwC0D2 logical name: /dev/snd/pcmC0D0c logical name: /dev/snd/pcmC0D0p logical name: /dev/snd/pcmC0D10p logical name: /dev/snd/pcmC0D2c logical name: /dev/snd/pcmC0D3p logical name: /dev/snd/pcmC0D7p logical name: /dev/snd/pcmC0D8p logical name: /dev/snd/pcmC0D9p version: 21 width: 64 bits clock: 33MHz capabilities: pm msi bus_master cap_list configuration: driver=snd_hda_intel latency=32 resources: irq:128 memory:df1a8000-df1abfff memory:df180000-df18ffff