diff --git a/src/compile/mark/encode/position-rect.ts b/src/compile/mark/encode/position-rect.ts
index 48fdfc2b407..a4d81787ab9 100644
--- a/src/compile/mark/encode/position-rect.ts
+++ b/src/compile/mark/encode/position-rect.ts
@@ -81,6 +81,7 @@ function defaultSizeRef(
         if (bandSize.band !== 1) {
           bandWidth = `${bandSize.band} * ${bandWidth}`;
         }
+        // TODO(#8351): make 0.25 here configurable
         return {signal: `max(0.25, ${bandWidth})`};
       } else if (bandSize.band !== 1) {
         log.warn(log.message.cannotUseRelativeBandSizeWithNonBandScale(scaleType));