@Dzhastina Akgül - As per the Video Chat Help Center article, Miro’s Video (and audio) chat uses Amazon Web Services. Perhaps there has a been a disruption in these services (deliberate or not) to Russia given the current conflict.

https://help.miro.com/hc/en-us/articles/360017572214-Video-chat#h_01F4GGDFY5MZN4MHKSHTWS7MDF

If you are noticing the video chat is not working, I take this to mean you have a paid Miro account. I would suggest opening a support ticket → https://help.miro.com/hc/en-us/articles/360020185799-How-to-contact-Miro-Support#h_01F010RXA0E1S9C0WFQYX75R6C