This is a section of the convert URLs plugin from Crowd Favorite with some modifications to handle our CMB2 fields that contain TinyMCE editors.

RAMP-convert-urls-CMB2.php

<?php

function sas_CMB2_convert() {
	$sas_CMB2_TinyMCE_fields = array(
		0 => array(
			"CMB2_group" => "repeat_group_name",  //name of the repeat group
			"CMB2_field" => "field_name"          //name of the field w/in the repeat group to translate
		)
	);

	return $sas_CMB2_TinyMCE_fields;
}


	
class cfcu_deploy_callbacks {
// buncha functions I didn't need to modify...

// Transfer Callback Methods
	
	public function cfcu_receive_callback($cfcu_settings) {
		global $wpdb;
		$success = true;
		$message = __('No posts to update', 'cfcu');
		$message = print_r($cfcu_settings, true);
		$messages = array();

		$prod_url = home_url('/', 'http');
		$prod_url = preg_replace('/^http:/', '', $prod_url);
		if (isset($cfcu_settings['guids']) && !empty($cfcu_settings['guids'])
				&& isset($cfcu_settings['staging_url']) && !empty($cfcu_settings['staging_url'])) {
			foreach ($cfcu_settings['guids'] as $guid => $true) {
				$post_id = cfd_get_post_id_by_guid($guid);
				$post = get_post($post_id);

				// Begin SAS customizations
				// We need to get the postmeta as well
				$meta = get_post_meta( $post_id );

				if (!$post) { 
					$messages[] = "couldn't get post $post_id from guid $guid";
					continue;
				}


				$updated_post = array();
				$updated_post['post_content'] = str_replace($cfcu_settings['staging_url'], $prod_url, $post->post_content);
				$updated_post['post_excerpt'] = str_replace($cfcu_settings['staging_url'], $prod_url, $post->post_excerpt);
				$result = $wpdb->update($wpdb->posts, $updated_post, array('ID' => $post->ID));


				// We also have to convert content within CMB2 custom fields
				// use WP functions to unserialize the meta, then update it after the url has been corrected.

				//we want to do this conditionally, only if we have postmeta to be translated
				//and we want to do this for any number of different CMB2 fields that contain a TinyMCE editor.


				$sas_fields = sas_CMB2_convert();  // get our array of fields that need URL conversion
				$updated_meta = array();

				foreach ( $sas_fields as $fields ) {

					$my_CMB2_group_name = $fields["CMB2_group"];  //meta_key in postmeta
					$my_CMB2_field_name = $fields["CMB2_field"];    //after unserialization, name of field where our data to translate is kept
					$my_CMB2_group_value = maybe_unserialize( $meta[$my_CMB2_group_name][0] );

					if (isset ( $my_CMB2_group_value ) ) {

						$a = 0;  //counter
						foreach ( $my_CMB2_group_value as $value ) {

							$updated_meta[ $my_CMB2_group_name ] = str_replace( $cfcu_settings['staging_url'], $prod_url, $value[ $my_CMB2_field_name ] );
							$value[ $my_CMB2_field_name ] = $updated_meta[ $my_CMB2_group_name ];

							//push the updated value back onto the original unserialized postmeta array
							$my_CMB2_group_value[ $a ][ $my_CMB2_field_name ] = $updated_meta[ $my_CMB2_group_name ];

							$a ++;

						}

						// update_post_meta takes care of serialization for us
						$meta_result = update_post_meta( $post->ID, $my_CMB2_group_name, $my_CMB2_group_value );
					}

				}

				if ($result === false) {
					$success = false;
					$messages[] = sprintf(__('error updating %s %d (%s)', 'cfcu'), $post->post_type, $post->ID, $post->post_title);
				}
				else {
					$messages[] = sprintf(__('updated %s %d (%s)', 'cfcu'), $post->post_type, $post->ID, $post->post_title);
				}
			}

		}
		if (!empty($messages)) {
			$message = sprintf(__('Results: %s', 'cfcu'), implode('; ', $messages));
		}

		return array(
			'success' => $success,
			'message' => $message
		);
	}
}