SUMMARY
In a setup where an external monitor is connected to the NVIDIA GPU while the internal monitor is connected to the Intel GPU (The issue persists even when the refresh rates of both monitors are set to the same value.) , and KWin(wayland) is set to render via the Intel GPU, the system constantly spams the following error message:
"Invalid framebuffer status: GL_FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT"

This results in a sharp increase in both single-core CPU usage and temperature. Setting the environment variable KWIN_FORCE_SW_CURSOR=1 completely resolves all these symptoms.

STEPS TO REPRODUCE
1. Connect an external monitor to the NVIDIA graphics card.  
2. Ensure KWin (Wayland) is rendering via the Intel GPU (default behavior).
3. Move the mouse cursor or open a new window on the external monitor to perform tasks.

OBSERVED RESULT
Significant spike in single-core CPU usage and temperature. The system logs are abnormally flooded with the error message: 'Invalid framebuffer status: GL_FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT'.
The issue persists even when the refresh rates of both monitors are set to the same value.

EXPECTED RESULT
The CPU usage should remain normal without error messages, and the hardware cursor should function correctly without issues in a dual GPU configuration.

Operating System: Arch Linux 
KDE Plasma Version: 6.6.4
KDE Frameworks Version: 6.25.0
Qt Version: 6.11.0
Kernel Version: 7.0.2-arch1-1 (64-bit)
Graphics Platform: Wayland
Processors: 32 × 13th Gen Intel® Core™ i9-13900HX
Memory: 32 GiB of RAM (31.1 GiB usable)
Graphics Processor 1: Intel® Graphics
Graphics Processor 2: NVIDIA GeForce RTX 4060 Laptop GPU
Manufacturer: Acer
Product Name: Predator PHN16-71
System Version: V1.18

ADDITIONAL INFORMATION
In addition to using KWIN_FORCE_SW_CURSOR=1, the following actions also resolve the issue:

- Forcing KWin to render using the NVIDIA GPU (via KWIN_DRM_DEVICES).

- Or disconnecting the external monitor.

These observations suggest that the symptoms only occur when the Intel GPU handles rendering in a multi-GPU setup with an active external output.

The log file grows excessively large, exceeding 22MB after only a brief boot-up and session. While I cannot attach the full log due to its size, the vast majority of the entries consist of the following error: 'Invalid framebuffer status: GL_FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT'.
Please let me know if you need the detailed logs. Since there is a 4MB attachment limit here (and my log exceeds 22MB), I will find an alternative way to share the file, such as using an external hosting service or providing a truncated snippet, if required.