Hi there

We are using Zendesk chat.

When the browser zoom is used to scale content to 400%, Zendesk chat also zooms to 400% covering the content of the website/page. This fails accessibility.

Please try zooming your web browser to 400%. 
(PC: Ctrl and + keyboard key)

For people with low vision, enlarged text with reflow enables reading.
Is there a way when users zooms web browser to 400%, Zendesk chat still remains at 100%?

Reference 
https://www.w3.org/WAI/WCAG21/Understanding/reflow.html

Thank you