Reproduction steps (requires a ray tracing capable GPU):
1. Open the attached “IN-61251 Recorder Frame Accumulation Bug.zip“ project
2. Open the “OutdoorsScene”
3. In the Recorder window, Press the “+ Add Recorder” button > “Image Sequence”
4. Under the Input category, check the “Accumulation” property and increase the “Samples” to 128 (or some other amount which produces good enough results)
5. Press the “START RECORDING” button in the Recorder window
6. Observe the Game view (wait for a few frames to render)
7. Resize the Game view window (resizing from the bottom edge/bottom-right corner reproduces the issue the most consistently)
8. Wait for a few more frames to render (observe the rendered frames in the “Recordings” folder to see when the rendered output becomes grainy)
9. (Optional) press the “STOP RECORDING” button in the Recorder window

Expected result: The rendered frames never become grainy
Actual result: All of the newly rendered frames are very grainy, lacking samples per pixel and denoising

Reproducible with: 4.0.0-pre.3 (2021.3.34f1), 4.0.2 (2022.3.17f1), 5.1.0-pre.1 (2023.2.6f1, 2023.3.0b3)

Reproduced on: Windows 11 Pro (23H2)
Not reproduced on: No other environment tested

Notes:
- Reproducible in a new project
- Both Intel Open Image Denoise and NVIDIA Optix Denoiser are affected by the issue (denoising is not available in 2021.3.34f1 but the issue is still clearly visible due to the lack of samples per pixels)
- The issue makes it impossible for the reporter to work on remote machines as the display resolution changes often while working in teams
- Changing the Game view resolution in the Aspect ratio menu or moving the Game view to another monitor with a different resolution and/or UI scaling can reproduce the issue as well
- Reproducible with a “Movie” Recorder as well