diff --git a/packages/core/database/lib/query/helpers/populate/apply.js b/packages/core/database/lib/query/helpers/populate/apply.js
index 130f2aa093..1138bab261 100644
--- a/packages/core/database/lib/query/helpers/populate/apply.js
+++ b/packages/core/database/lib/query/helpers/populate/apply.js
@@ -446,6 +446,11 @@ const morphToMany = async (input, ctx) => {
     .where({
       [joinColumn.name]: referencedValues,
       ...(joinTable.on || {}),
+      // If the populateValue contains an "on" property,
+      // only populate the types defined in it
+      ...('on' in populateValue
+        ? { [morphColumn.typeColumn.name]: Object.keys(populateValue.on) }
+        : {}),
     })
     .orderBy([joinColumn.name, 'order'])
     .execute({ mapResults: false });
@@ -482,14 +487,10 @@ const morphToMany = async (input, ctx) => {
       continue;
     }
 
-    if (on && on[type]) {
-      Object.assign(typePopulate, on[type]);
-    }
-
     const qb = db.entityManager.createQueryBuilder(type);
 
     const rows = await qb
-      .init(typePopulate)
+      .init(on && type in on ? on[type] : typePopulate)
       .addSelect(`${qb.alias}.${idColumn.referencedColumn}`)
       .where({ [idColumn.referencedColumn]: ids })
       .execute({ mapResults: false });
@@ -546,6 +547,8 @@ const morphToOne = async (input, ctx) => {
   }, {});
 
   const map = {};
+  const { on, ...typePopulate } = populateValue;
+
   for (const type of Object.keys(idsByType)) {
     const ids = idsByType[type];
 
@@ -558,7 +561,7 @@ const morphToOne = async (input, ctx) => {
     const qb = db.entityManager.createQueryBuilder(type);
 
     const rows = await qb
-      .init(populateValue)
+      .init(on && type in on ? on[type] : typePopulate)
       .addSelect(`${qb.alias}.${idColumn.referencedColumn}`)
       .where({ [idColumn.referencedColumn]: ids })
       .execute({ mapResults: false });
diff --git a/packages/core/utils/lib/convert-query-params.js b/packages/core/utils/lib/convert-query-params.js
index 4c11510375..a6b6cadb26 100644
--- a/packages/core/utils/lib/convert-query-params.js
+++ b/packages/core/utils/lib/convert-query-params.js
@@ -17,6 +17,7 @@ const {
   isPlainObject,
   cloneDeep,
   get,
+  mergeAll,
 } = require('lodash/fp');
 const _ = require('lodash');
 const parseType = require('./parse-type');
@@ -185,14 +186,13 @@ const convertPopulateObject = (populate, schema) => {
       return acc;
     }
 
-    if (subPopulate && subPopulate.on) {
+    if (subPopulate && 'on' in subPopulate) {
       return {
         ...acc,
         [key]: {
-          ...subPopulate,
           on: Object.entries(subPopulate.on).reduce(
-            (newTypeSubPopulate, [type, typeSubPopulate]) => ({
-              ...newTypeSubPopulate,
+            (acc, [type, typeSubPopulate]) => ({
+              ...acc,
               [type]: convertNestedPopulate(typeSubPopulate, strapi.getModel(type)),
             }),
             {}
@@ -201,6 +201,25 @@ const convertPopulateObject = (populate, schema) => {
       };
     }
 
+    // TODO: Deprecated way of handling dynamic zone populate queries. It's kept as is,
+    // as removing it could break existing user queries but should be removed in V5.
+    if (attribute.type === 'dynamiczone') {
+      const populates = attribute.components
+        .map((uid) => strapi.getModel(uid))
+        .map((schema) => convertNestedPopulate(subPopulate, schema))
+        .map((populate) => (populate === true ? {} : populate)) // cast boolean to empty object to avoid merging issues
+        .filter((populate) => populate !== false);
+
+      if (isEmpty(populates)) {
+        return acc;
+      }
+
+      return {
+        ...acc,
+        [key]: mergeAll(populates),
+      };
+    }
+
     // NOTE: Retrieve the target schema UID.
     // Only handles basic relations, medias and component since it's not possible
     // to populate with options for a dynamic zone or a polymorphic relation