When Form auto-zoom on Mobile the Pinch doesn't work well

Which product are you using?
PDF.js Express Plus. (domain: kopjra.com)

PDF.js Express Version
UI version: ‘8.1.0’
Core version: ‘8.1.1’

Detailed description of issue
In mobile when the text field is tapped for text input there is a zoom to that text field. If one tries to zoom out using pinch it does not work, and sends the PDF in the viewer to a strange position and from there even the scroll is kind of lost. The only way to zoom out when in that position is usgin a double tap. This problem is more evident when using Safari on IOS, but it happens in Android with Chrome also.

Expected behaviour
We would expect the tap to work as it usually does. Thus zooming out the PDF in a controlled way without any jumps to strange position.

Does your issue happen with every document, or just one?
It happens on every document with a form

Code snippet
Here you can see a working integration from pur part:

Hello, I’m Ron, an automated tech support bot :robot:

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Hello luis.perezsanchez,

Im unable to reproduce any unintended jumping on our demo website: PDF.js Viewer Demo | PDF.js Express

  1. Can you try on there?
  2. Do you have any custom code that effects the viewer in any way?
  3. Can you provide a video of the jumping?

Best regards,
Tyler Gordon
Web Development Support Engineer