@cmallonee, this also happens without a gateway restart. I just observed it happen on Designer reconnect after being offline for a while due to VPN disconnection. session.device.type showed designer (correct) until the Designer reconnected to gateway, and then switched to browser (incorrect). Gateway hasn't been restarted for a month:
Designer was online yesterday. This doesn't seem to happen on all brief connection losses, but does happen enough to be annoying--especially when working with multiple Designers open that all need a restart to correct this.