Target probe VMAF much lower than final score.

[esiefker]

Using target mode, probes are getting much lower VMAF scores than the final encode. I am using --probe-video-params copy, I expected they'd be closer.

This is my command

        av1an -i intermediate.mkv \
            -o av1an_target93.mkv \
            --temp target93_temp \
            -l target93_log \
            --encoder svt-av1 \
	    --target-quality 93 \
	    --chunk-method lsmash \
	    --concat mkvmerge \
	    --probe-video-params copy \
	    --vmaf \
            -v "--preset 2 --keyint 420 --enable-qm 1 --enable-variance-boost 1" \
            --pix-format yuv420p10le \
            -x 0

Which gives this representative output.

2026-02-10T01:30:02.542162Z DEBUG encode_chunk{worker_id=0 total_chunks=315 chunk_index="00192"}: av1an_core::target_quality: chunk 00192: Target=92.07-93.93, Metric=vmaf, P-Rate=1, 352 frames, P-Video-Params: --preset 2 --keyint 420 --enable-qm 1 --enable-variance-boost 1
       TQ-Probes: [(15.00, 88.98), (23.75, 85.31), (32.50, 80.08)]
       Final Q=15.00, Final Score=88.98
2026-02-10T01:31:21.727749Z DEBUG encode_chunk{worker_id=1 total_chunks=315 chunk_index="00147"}: av1an_core::target_quality: chunk 00147: Target=92.07-93.93, Metric=vmaf, P-Rate=1, 352 frames, P-Video-Params: --preset 2 --keyint 420 --enable-qm 1 --enable-variance-boost 1
       TQ-Probes: [(15.00, 90.07), (23.75, 85.77), (32.50, 79.45)]
       Final Q=15.00, Final Score=90.07
2026-02-10T01:32:18.551723Z DEBUG encode_chunk{worker_id=0 total_chunks=315 chunk_index="00133"}: av1an_core::target_quality: chunk 00133: Target=92.07-93.93, Metric=vmaf, P-Rate=1, 348 frames, P-Video-Params: --preset 2 --keyint 420 --enable-qm 1 --enable-variance-boost 1
       TQ-Probes: [(16.25, 92.24), (17.50, 91.53), (23.75, 87.59), (32.50, 79.93)] Early Skip Within Tolerance
       Final Q=16.25, Final Score=92.24

It's having to go into the teens to get close to my target VMAF of 93.
On average, the Q=16.8 for a VMAF of 91.5
When I run vmaf on the final file, I get 96.2

When I encode to CRF 30 using the same parameters, I get a VMAF of 93.8

My source is an already bob deinterlaced PAL DVD at 50fps.
Stream #0:0: Video: ffv1, yuv420p10le(tv, progressive), 720x576, 50 fps, 50 tbr, 1k tbn

Is this expected, or am I doing something wrong?