This was fixed after an update before yesterday.
As a workaround I blocked the access to my camera for three days, I have tested again and it is not happening anymore.
This notification from the browser is a little bit confusing, I had to click on the Manage button and allow the microphone to use WebRTC.

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Paulo Mesquita
Spark NZ Trading
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Original Message:
Sent: 06-25-2020 15:30
From: Patrick Rada
Subject: Webcam activating when logging into PureCloud
I'm told by CC that there is/was an open internal dev ticket on this and that as a work around you can toggle the video chat icon. Haven't had a report come in that I can try that with.
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Patrick Rada
Keypath Education LLC
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Original Message:
Sent: 06-25-2020 03:31
From: John Coyne
Subject: Webcam activating when logging into PureCloud
Hello
a meaningful update would be useful please
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John Coyne
FirstCare Ltd.