Digital blocky glitches/artifacts appear in some resulting HEVC videos after using the Multi-pass option or Encoder type: Slower in Compressor

Hello.

First of all, let's start with my tech specs: 16" MacBook Pro with Apple M4 Pro (14-core CPU, 20-core GPU, and 16-core Neural Engine) and 48 GB RAM. My OS is Sequoia 15.4.1. I work in Final Cut Pro v11.1 and Compressor v4.10. I also used HandBrake v1.9.2 for some additional tests.

I work with screen recordings of different resolutions (MPEG-4 AAC, H.264, 60 FPS) captured via the default app. Edit them in Final Cut Pro, and send to Compressor using my custom preset (MPEG-4 AAC, HEVC, 30 FPS, 2200 kbps, 8-Bit Color (4-2-0)). Some of resulting videos show digital blocky glitches/artifacts in some places if I check the Multi-Pass option or choose Encoder type: Slower (higher quality) in Compressor. However, if I choose Encoder type: Slower (higher quality) digital glitches are not so strong as with Multi-Pass, but appear in the same places. Blocky glitches/artifacts look like the bad image quality during a video call on What's App when you have connection issues like slow Internet speed, etc.

I tried to reinstall Compressor, but it did not help as glitches continued to appear in same resulting videos, but just in other places. Then I exported files from Final Cut Pro using the default destination Export File (Timecode, Apple ProRes 422, Linear PCM) and opened in Compressor to encode; the resulting videos showed glitches as well. Also, I saved my custom Compressor preset as a destination in Final Cut Pro, and used it. Resulting videos were without glitches, but less detailed compared to ones gathered via Compressor. Looks like the Multi-pass option does not work if you use Compressor presets in Final Cut Pro.

Finally, I decided to check if glitches are a specific problem of Compressor, and used HandBrake as it has H.265 (VideoToolbox) and Multi-pass. In addition, HandBrake allows to enable the VideoToolbox hardware decoders and use them in combination with software encoders via Preferences. Well, I got the following results:

1. H.265 + Multi-pass -> no glitches;
2. H.265 (VideoToolbox) + Multi-pass -> no glitches;
3. H.265 (VideoToolbox) + Multi-pass + Enabled VideoToolbox hardware decoders -> no glitches;
4. H.265 (VideoToolbox) + Multi-pass + Enabled VideoToolbox hardware decoders + Enabled combination with software encoders -> glitches;
5. H.265 (VideoToolbox) + Disabled Multi-pass + Enabled VideoToolbox hardware decoders + Enabled combination with software encoders -> no glitches.

From what I see, HandBrake shows that it is not a Compressor problem.

Did someone experience something same with digital glitches? What can it be? Is there any fix?

Based on the info above, I hope, it is a software problem that will be fixed in future updates of macOS, and the Media Engine or other hardware stuff are not damaged.