Avats started blocking Megasync app,but for what reason?

Hello,i"m using avast internet security,second day,avast blocked and added megasync app for windows in to virus chest,early is been everything fine,so where is the problem?

Without knowing more, I would say a new detection that is added to the vps is causing it.

https://www.avast.com/false-positive-file-form.php