[Bug]: Boot race between Plymouth graphical splash and display manager (greetd / Plasma Login) on NVIDIA

### Kernel

linux-cachyos 7.1.5-1

### Desktop Environment / Window Manager

KDE Plasma

### CPU

12th Gen Intel(R) Core(TM) i9-12900H

### GPU / Driver

NVIDIA GeForce RTX 3050

### Description

### Pre-flight checklist

- [x] Searched for existing issues
- [x] Reproducible on latest CachyOS

### Hardware

Laptop
Intel Alder Lake iGPU + NVIDIA dGPU
Bootloader: systemd-boot

### Kernel

linux-cachyos 7.1.5-1

### Display Managers Tested

- greetd + ReGreet
- Plasma Login

Both exhibit the same behavior.

### Description

After a recent update, the system frequently fails to present the login screen during boot.

If I switch to a TTY and manually start the display manager, it works correctly.

### Experiments

1. `quiet splash` + greetd
- FAIL

2. `quiet splash` + 5 second ExecStartPre sleep
- PASS

3. Removed `splash` from `/etc/kernel/cmdline`
- PASS consistently without any delay

Plymouth remains in the initramfs (`HOOKS=(... plymouth ...)`), but removing only the `splash` kernel parameter resolves the issue.

### Evidence

`systemd-analyze critical-chain greetd.service`

greetd starts immediately after `plymouth-quit-wait.service`.

Bug report:
https://paste.cachyos.org/p/32a4674
https://paste.cachyos.org/p/958b95f

successful log: https://paste.cachyos.org/p/7bd036d

Additional logs available on request.

Happened on both greetd hyprland and plasmalogin kde

### Steps to Reproduce

## Steps to reproduce

1. Update CachyOS to the latest packages.
2. Ensure the kernel command line contains the `splash` boot parameter (e.g. `quiet splash`).
3. Reboot.
4. The system hangs at the CachyOS Plymouth splash screen and the display manager never appears.

## Workaround

1. Remove the `splash` kernel boot parameter from the kernel command line.
2. Regenerate the boot entry (`kernel-install`).
3. Reboot.
4. The system boots normally and the display manager appears.

## Additional information

- Reproduced with both Plasma Login and greetd/ReGreet.
- Adding a 5-second delay before starting the display manager also works around the issue.
- Removing only the `splash` kernel boot parameter resolves the problem while leaving Plymouth installed in the initramfs.

### Expected Behavior

## Expected behavior

After boot, the system should transition from the Plymouth splash screen to the display manager login screen (tested with Plasma Login and greetd/ReGreet).

### Actual Behavior

## Actual behavior

The system remains stuck at the Plymouth splash screen and never reaches the display manager login screen.

### Logs / Error Messages

https://paste.cachyos.org/p/32a4674

### Additional Context

_No response_

Start with systemd-analyze critical-chain greetd.service and compare it with plymouth-quit-wait.service, then inspect the /etc/kernel/cmdline splash parameter and the initramfs HOOKS entry containing plymouth. Reproduce with and without splash and with the reported startup delay; done means the system reliably transitions from Plymouth to either tested display manager without a manual TTY start.

Written by the indexing model from the issue text.