This seems to be an issue with Edge 88.0.705.50. In higher version, Edge 89.0.767.0, the flag comes back again:
I think the issue will be fixed in future version of Edge Stable. You can wait for the updates and download Edge Dev to test your app as a workaround for now.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…