Flicker bug on Harmony Portal effect

Hi, this has been annoying me for quite some time now. The Harmony Portal flickers every few seconds. The portal's background disappears for a moment and then reappears, making it pretty jaring to look at. Link to 2 short clips for reference:
https://imgur.com/a/VSEcbhD

In the product video this flicker does not happen. Instead the effect is nice and smooth all throughout. As such I believe that this portal effect is bugged and would like to get it fixed.
https://www.youtube.com/watch?v=JU3zWizoqic

edit:
Just wanted to add that I tested this on all 3 renderers and with all possible graphics settings. None of them have any impact on this. The bug always persists.