When copying an asset to clipboard (using Ctrl/Cmd + C) SVG data in clipboard doesn't have custom image pattern. However, if the asset is exported the image pattern is included in the SVG file.

MacOS Monterey 12.5 Apple M1 Pro
Adobe Illustrator 26.5

Steps to reproduce:
1. Download and open FlowerDress.ai - https://drive.google.com/file/d/1vKlyAV2ahPACBnPpe8TUGUXnpznQ3rIf/view?usp=sharing
2. Make sure it looks like on the screenshot - https://drive.google.com/file/d/1Ji71P6F5nw3O5KAjfjhp_pmKmCpZNLy0/view?usp=sharing
3. Select the dress and hit Ctrl/Cmd + C.
4. Paste it in any code editor (vscode).

Actual Result - https://drive.google.com/file/d/10jE12CQuTzYf0ZCh4paWJor4RDRot-aj/view?usp=sharing
<?xml version="1.0" encoding="UTF-8"?>
<svg id="Layer_1" data-name="Layer 1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" viewBox="0 0 239.18 354.03">
<defs>
<style>
...
</style>
<pattern id="Flower_Pattern" data-name="Flower Pattern" x="0" y="0" width="208.98" height="278.99" patternTransform="translate(-426.6 -223.5)" patternUnits="userSpaceOnUse" viewBox="0 0 208.98 278.99">
<rect class="cls-1" width="208.98" height="278.99"/>
</pattern>
</defs>
...
</svg>

Note that <pattern> doesn't include an <image> and if this was rendered in the browser the dress would have been empty.

Next - export the dress asset:
1. Select the dress.
2. Export selection as SVG.

Actual result:
https://drive.google.com/file/d/1g4bhJTUW3vT_uWI27XsGxlxefEvYKuPn/view?usp=sharing
The file that was exported includes <image> in <pattern>

Expected result: Clipboard data is the same as exported data and includes the image pattern.