diff --git a/pcsx2/GS/Renderers/HW/GSTextureCache.cpp b/pcsx2/GS/Renderers/HW/GSTextureCache.cpp
index 3f9a73bb56..7948104608 100644
--- a/pcsx2/GS/Renderers/HW/GSTextureCache.cpp
+++ b/pcsx2/GS/Renderers/HW/GSTextureCache.cpp
@@ -9459,6 +9459,31 @@ GSTextureCache::HashCacheKey GSTextureCache::HashCacheKey::Create(const GIFRegTE
 
 	ret.TEX0Hash = FinishBlockHash(hash_st);
 
+	// ★ CROSS-VERSION PROBE (diagnostic builds only).
+	//
+	// Two builds ask for completely disjoint TEX0 hashes for the same on-screen font: nine values
+	// on 2.6.6, eight now, no overlap, same palette hash, same 32x32 PSMT4. Every hashing function
+	// involved is byte-identical between them, so the DATA being hashed differs -- and the key
+	// records only the region's width and height, never where it starts or which address it came
+	// from. Print the things the key throws away, so the two logs can be diffed directly instead
+	// of guessed at.
+	if (psm.pal != 0)   // any paletted texture; the cap below keeps the volume sane
+	{
+		static u32 probes = 0;
+		if (probes < 12)
+		{
+			probes++;
+			Console.WriteLnFmt("TCPROBE tex0hash={:016x} clut={:016x} TBP0={:05x} TBW={} PSM={} TW={} TH={} "
+				"region=({},{})-({},{}) lod={} first={:02x}{:02x}{:02x}{:02x}{:02x}{:02x}{:02x}{:02x}",
+				ret.TEX0Hash, ret.CLUTHash, static_cast<u32>(TEX0.TBP0), static_cast<u32>(TEX0.TBW),
+				static_cast<u32>(TEX0.PSM), static_cast<u32>(TEX0.TW), static_cast<u32>(TEX0.TH),
+				region.GetMinX(), region.GetMinY(), region.GetMaxX(), region.GetMaxY(),
+				lod ? 1 : 0,
+				s_unswizzle_buffer[0], s_unswizzle_buffer[1], s_unswizzle_buffer[2], s_unswizzle_buffer[3],
+				s_unswizzle_buffer[4], s_unswizzle_buffer[5], s_unswizzle_buffer[6], s_unswizzle_buffer[7]);
+		}
+	}
+
 	return ret;
 }