How do i recover deleted messages on iCloud

Unfortunately, it is not possible to recover deleted messages from iCloud. Once the messages are deleted and iCloud has synced, they are gone. This is the agreement you make with Apple, it gives you an assurance that when you delete something, it will not appear again. Conversely, it is of course annoying when you delete something that should not be deleted.

Here's what Apple writes:

When you turn on Messages in iCloud, your message history is updated automatically on all of your devices. That way, you always have the same view everywhere you use iMessage. When you delete a message, photo, or conversation on one device, it’s removed from all of your devices. And since all of your attachments are stored in iCloud, you can save space on your device.

You can use Messages in iCloud on your iPhone, iPad, iPod touch, Apple Watch, and Mac. For your privacy, Messages in iCloud is end-to-end encrypted, which means you can't view or access Messages online via browser.

Use Messages in iCloud - Apple Support