My memojis have just disappeared since I updated to 13.4.1

Hello Katnipmike,

Thanks for using the Apple Support Communities! I understand that you are unable to find your Memoji after updating your software. Let’s take a look and see what we can do. I'm happy to help!

Let's follow this resource that I was able to gather. You do have to select the App Store icon in Messages to get the shortcuts with Memoji being one of them.

How to use Memoji on your iPhone or iPad Pro

Specifically in Messages, "Use your Memoji"

To send an animated Memoji or a Memoji sticker:

1. Open Messages and tap the Compose button  to start a new message. Or go to an existing conversation.
2. Tap the Animoji button , then swipe left to pick your Memoji.
3. Tap the Record button  to record and  to stop. You can record for 30 seconds. To choose a different Memoji with the same recording, tap another Memoji that you created. To create a Memoji sticker, touch and hold the Memoji and drag it to the message thread. To delete a Memoji, tap the Trash button .
4. Tap the Send button .

To use an animated Animoji and Memoji, you need a compatible iPhone or iPad Pro.

Cheers!