diff --git a/jOOQ/src/main/java/org/jooq/impl/AbstractContext.java b/jOOQ/src/main/java/org/jooq/impl/AbstractContext.java
index 31d29b29a4..d41e118b53 100644
--- a/jOOQ/src/main/java/org/jooq/impl/AbstractContext.java
+++ b/jOOQ/src/main/java/org/jooq/impl/AbstractContext.java
@@ -54,6 +54,8 @@ import static org.jooq.impl.Tools.EMPTY_CLAUSE;
 import static org.jooq.impl.Tools.EMPTY_QUERYPART;
 import static org.jooq.impl.Tools.lazy;
 import static org.jooq.impl.Tools.traverseJoins;
+import static org.jooq.impl.Tools.BooleanDataKey.DATA_MULTISET_CONDITION;
+import static org.jooq.impl.Tools.BooleanDataKey.DATA_MULTISET_CONTENT;
 import static org.jooq.impl.Tools.BooleanDataKey.DATA_NESTED_SET_OPERATIONS;
 import static org.jooq.impl.Tools.BooleanDataKey.DATA_OMIT_CLAUSE_EVENT_EMISSION;
 import static org.jooq.impl.Tools.BooleanDataKey.DATA_RENDER_IMPLICIT_JOIN;
@@ -106,6 +108,7 @@ import org.jooq.conf.SettingsTools;
 import org.jooq.conf.StatementType;
 import org.jooq.exception.DataAccessException;
 import org.jooq.impl.QOM.UEmpty;
+import org.jooq.impl.Tools.BooleanDataKey;
 import org.jooq.impl.Tools.DataKey;
 
 
@@ -263,7 +266,24 @@ abstract class AbstractContext<C extends Context<C>> extends AbstractScope imple
 
     @Override
     public final C visit(Condition part) {
-        return visit((QueryPart) part);
+
+        // [#16310] The MULTISET content flag needs to be reset for any non
+        //          multiset projection context. For example, in any Condition.
+        //          While Conditions can be projected, they're projecting a BOOLEAN,
+        //          not nested records or collections
+        if (TRUE.equals(data(DATA_MULTISET_CONTENT))) {
+            try {
+                data(DATA_MULTISET_CONTENT, false);
+                visit((QueryPart) part);
+            }
+            finally {
+                data(DATA_MULTISET_CONTENT, true);
+            }
+        }
+        else
+            visit((QueryPart) part);
+
+        return (C) this;
     }
 
     @Override
diff --git a/jOOQ/src/main/java/org/jooq/impl/SelectIsNotNull.java b/jOOQ/src/main/java/org/jooq/impl/SelectIsNotNull.java
index b7d17e61ed..5134406160 100644
--- a/jOOQ/src/main/java/org/jooq/impl/SelectIsNotNull.java
+++ b/jOOQ/src/main/java/org/jooq/impl/SelectIsNotNull.java
@@ -42,10 +42,11 @@ import static org.jooq.impl.DSL.selectCount;
 import static org.jooq.impl.Keywords.K_IS_NOT_NULL;
 import static org.jooq.impl.SubqueryCharacteristics.PREDICAND;
 import static org.jooq.impl.Tools.allNotNull;
+import static org.jooq.impl.Tools.exactlyOne;
+import static org.jooq.impl.Tools.flattenCollection;
 import static org.jooq.impl.Tools.visitSubquery;
 
 import org.jooq.Clause;
-import org.jooq.Condition;
 import org.jooq.Context;
 import org.jooq.Function1;
 import org.jooq.Select;
@@ -78,7 +79,8 @@ final class SelectIsNotNull extends AbstractCondition implements QOM.SelectIsNot
         if (SelectIsNull.EMULATE_NULL_QUERY.contains(ctx.dialect())) {
 
             // [#11011] Avoid the RVE IS NULL emulation for queries of degree 1
-            if (select.getSelect().size() == 1) {
+            // [#16319] Flatten embeddables to find collection size
+            if (exactlyOne(flattenCollection(select.getSelect()))) {
                 acceptStandard(ctx);
             }
             else {
diff --git a/jOOQ/src/main/java/org/jooq/impl/SelectIsNull.java b/jOOQ/src/main/java/org/jooq/impl/SelectIsNull.java
index 658039e97e..95589d8a6e 100644
--- a/jOOQ/src/main/java/org/jooq/impl/SelectIsNull.java
+++ b/jOOQ/src/main/java/org/jooq/impl/SelectIsNull.java
@@ -73,6 +73,8 @@ import static org.jooq.impl.DSL.selectCount;
 import static org.jooq.impl.Keywords.K_IS_NULL;
 import static org.jooq.impl.SubqueryCharacteristics.PREDICAND;
 import static org.jooq.impl.Tools.allNull;
+import static org.jooq.impl.Tools.exactlyOne;
+import static org.jooq.impl.Tools.flattenCollection;
 import static org.jooq.impl.Tools.visitSubquery;
 
 import java.util.Set;
@@ -113,7 +115,8 @@ final class SelectIsNull extends AbstractCondition implements QOM.SelectIsNull {
         if (EMULATE_NULL_QUERY.contains(ctx.dialect())) {
 
             // [#11011] Avoid the RVE IS NULL emulation for queries of degree 1
-            if (select.getSelect().size() == 1) {
+            // [#16319] Flatten embeddables to find collection size
+            if (exactlyOne(flattenCollection(select.getSelect()))) {
                 acceptStandard(ctx);
             }
             else {
diff --git a/jOOQ/src/main/java/org/jooq/impl/Tools.java b/jOOQ/src/main/java/org/jooq/impl/Tools.java
index 9f061eac66..e4f58e906e 100644
--- a/jOOQ/src/main/java/org/jooq/impl/Tools.java
+++ b/jOOQ/src/main/java/org/jooq/impl/Tools.java
@@ -6691,6 +6691,20 @@ final class Tools {
         return !i.hasNext();
     }
 
+    static final boolean exactlyOne(Iterable<?> it) {
+        if (it == null)
+            return false;
+        else if (it instanceof Collection<?> c)
+            return c.size() == 1;
+
+        Iterator<?> i = it.iterator();
+        return i.hasNext() && true_(i.next()) && !i.hasNext();
+    }
+
+    static final boolean true_(Object o) {
+        return true;
+    }
+
     static final boolean isNotEmpty(Object[] array) {
         return !isEmpty(array);
     }