To pass an array of URLs to the Multi Image field in Webflow's API for updating, you should follow the correct format. Each URL should be enclosed in double quotation marks and separated by a comma.
Here's an example of how you can pass an array of URLs to the Multi Image field:
```javascript
"images": ["https://example.com/image1.jpg", "https://example.com/image2.jpg", "https://example.com/image3.jpg"]
```
Make sure the field name in the API request matches the Multi Image field name in your Webflow CMS. In this example, the field name is "images". Replace it with the corresponding field name in your project.
It's important to note that multi-image fields in the Webflow CMS can accept up to 100 images. If you exceed this limit, you may encounter issues while trying to update or save the data.