fix: experimental solution

inc/admin.php

@@ -275,6 +275,12 @@ function ppom_admin_save_form_meta() {
 		wp_send_json( $resp );
 	}
 
+	if ( is_string( $_REQUEST['ppom'] ) ) {
+		$ppom_encoded = $_REQUEST['ppom'];
+		parse_str( $ppom_encoded, $ppom_decoded);
+		$_REQUEST['ppom'] = $ppom_decoded;
+	}
+
 	global $wpdb;
 
 	extract( $_REQUEST );
@@ -450,6 +456,12 @@ function ppom_admin_update_form_meta() {
 	}
 	global $wpdb;
 
+	if ( is_string( $_REQUEST['ppom'] ) ) {
+		$ppom_encoded = $_REQUEST['ppom'];
+		parse_str( $ppom_encoded, $ppom_decoded);
+		$_REQUEST['ppom'] = $ppom_decoded;
+	}
+
 	$ppom_meta    = isset( $_REQUEST['ppom_meta'] ) ? $_REQUEST['ppom_meta'] : $_REQUEST['ppom'];
 	$product_meta = apply_filters( 'ppom_meta_data_saving', (array) $ppom_meta, $productmeta_id );
 	$product_meta = ppom_sanitize_array_data( $product_meta );

js/admin/ppom-admin.js

@@ -128,10 +128,24 @@ jQuery(function($) {
         jQuery(".ppom-meta-save-notice").html('<img src="' + ppom_vars.loader + '">').show();
 
         $('.ppom-unsave-data').remove();
+
+        const formData = new FormData();
+        const ppomFields = new URLSearchParams();
+
+        // NOTE: since the request is to big for small values of `max_input_vars`, we will send the PPOM fields as a single string.
+        (new FormData(this)).forEach(( value, key) => {
+            if ( key.startsWith('ppom[') && typeof value === 'string' ) {
+                ppomFields.append( key, value );
+            } else {
+                formData.append(key, value);
+            }
+        });
+
+        formData.append('ppom', ppomFields.toString());
 
         fetch(ajaxurl, {
             method: 'POST',
-            body: new FormData(this)
+            body: formData
         })
         .then(response => response.json())
         .then(resp => {