diff --git a/src/av1.c b/src/av1.c
index e47fb5d..727ffd8 100644
--- a/src/av1.c
+++ b/src/av1.c
@@ -293,7 +293,21 @@ static void av1_fill_frame(VADecPictureParameterBufferAV1 *picture,
 		ctrl->cdef.uv_sec_strength[i] = uv & 0x03;
 	}
 
-	/* ---- loop_restoration ---- (F3) */
+	/* ---- loop_restoration ---- (F3)
+	 * Phase 5 review Amendment 1 was REVERTED. The reviewer proposed
+	 * remap = {NONE, SWITCHABLE, WIENER, SGRPROJ} (Kwiboo's table)
+	 * based on AV1 spec FrameRestoreType wire encoding
+	 * {NONE=0, SWITCHABLE=1, WIENER=2, SGRPROJ=3} differing from V4L2's
+	 * {NONE=0, WIENER=1, SGRPROJ=2, SWITCHABLE=3}. Empirically applying
+	 * that permutation regressed ALL tests (allintra 10/10 → 0/10) —
+	 * so either VAAPI's yframe_restoration_type is NOT the raw spec
+	 * value (already-remapped to V4L2 enum semantics?), or vpu981
+	 * interprets the V4L2 enum values via a different mapping than
+	 * the V4L2 uAPI header documents. Per
+	 * [[feedback_review_empirical_over_theoretical]] keep the
+	 * identity mapping that empirically works; revisit if a
+	 * restoration-using fixture surfaces a real decode bug.
+	 */
 	{
 		uint8_t remap[4] = {
 			V4L2_AV1_FRAME_RESTORE_NONE,
diff --git a/src/picture.c b/src/picture.c
index 785b4a4..ef09064 100644
--- a/src/picture.c
+++ b/src/picture.c
@@ -390,6 +390,18 @@ VAStatus RequestBeginPicture(VADriverContextP context, VAContextID context_id,
 	 */
 	if (surface_object->current_slot != NULL)
 		surface_unbind_slot(driver_data, surface_object);
+
+	/*
+	 * AV1 Phase 5 review Amendment 4: clear any stale
+	 * linked_decode_surface_id from a prior film_grain display→decode
+	 * link. If ffmpeg-vaapi recycles a former display surface as a
+	 * decode target, BeginPicture binds a fresh slot — but without
+	 * this reset, copy_surface_to_image's link-follow would still
+	 * borrow from the now-stale linked surface and serve wrong data.
+	 * Cleared unconditionally (cheap) so the next AV1 grain frame
+	 * re-establishes the link if needed.
+	 */
+	surface_object->linked_decode_surface_id = VA_INVALID_SURFACE;
 	{
 		struct cap_pool_slot *cap_slot =
 			cap_pool_acquire(&driver_data->capture_pool, surface_id);