diff --git a/spark/v3.5/spark/src/main/java/org/apache/iceberg/spark/actions/RewriteTablePathSparkAction.java b/spark/v3.5/spark/src/main/java/org/apache/iceberg/spark/actions/RewriteTablePathSparkAction.java
index 11935e815e76..8aa5fbed1076 100644
--- a/spark/v3.5/spark/src/main/java/org/apache/iceberg/spark/actions/RewriteTablePathSparkAction.java
+++ b/spark/v3.5/spark/src/main/java/org/apache/iceberg/spark/actions/RewriteTablePathSparkAction.java
@@ -327,6 +327,9 @@ private Result rebuildMetadata() {
     Map<String, Long> rewrittenDeleteFileSizes = rewritePositionDeletes(deleteFilesToRewrite);
 
     // rebuild manifest files
+    // The size map holds one entry per distinct rewritten delete-file location. It is collected to
+    // the driver and broadcast to the manifest-rewrite tasks, so its footprint scales with the
+    // number of distinct delete files being rewritten rather than the table's total file count.
     RewriteContentFileResult rewriteManifestResult =
         rewriteManifests(
             deltaSnapshots,
diff --git a/spark/v4.0/spark/src/main/java/org/apache/iceberg/spark/actions/RewriteTablePathSparkAction.java b/spark/v4.0/spark/src/main/java/org/apache/iceberg/spark/actions/RewriteTablePathSparkAction.java
index 11935e815e76..8aa5fbed1076 100644
--- a/spark/v4.0/spark/src/main/java/org/apache/iceberg/spark/actions/RewriteTablePathSparkAction.java
+++ b/spark/v4.0/spark/src/main/java/org/apache/iceberg/spark/actions/RewriteTablePathSparkAction.java
@@ -327,6 +327,9 @@ private Result rebuildMetadata() {
     Map<String, Long> rewrittenDeleteFileSizes = rewritePositionDeletes(deleteFilesToRewrite);
 
     // rebuild manifest files
+    // The size map holds one entry per distinct rewritten delete-file location. It is collected to
+    // the driver and broadcast to the manifest-rewrite tasks, so its footprint scales with the
+    // number of distinct delete files being rewritten rather than the table's total file count.
     RewriteContentFileResult rewriteManifestResult =
         rewriteManifests(
             deltaSnapshots,
diff --git a/spark/v4.1/spark/src/main/java/org/apache/iceberg/spark/actions/RewriteTablePathSparkAction.java b/spark/v4.1/spark/src/main/java/org/apache/iceberg/spark/actions/RewriteTablePathSparkAction.java
index 11935e815e76..8aa5fbed1076 100644
--- a/spark/v4.1/spark/src/main/java/org/apache/iceberg/spark/actions/RewriteTablePathSparkAction.java
+++ b/spark/v4.1/spark/src/main/java/org/apache/iceberg/spark/actions/RewriteTablePathSparkAction.java
@@ -327,6 +327,9 @@ private Result rebuildMetadata() {
     Map<String, Long> rewrittenDeleteFileSizes = rewritePositionDeletes(deleteFilesToRewrite);
 
     // rebuild manifest files
+    // The size map holds one entry per distinct rewritten delete-file location. It is collected to
+    // the driver and broadcast to the manifest-rewrite tasks, so its footprint scales with the
+    // number of distinct delete files being rewritten rather than the table's total file count.
     RewriteContentFileResult rewriteManifestResult =
         rewriteManifests(
             deltaSnapshots,