Same! I switched back from Brave to Firefox last year after discovering that Sidebery has tab panels (which I think Arc calls workspaces) that can be set to use the same Firefox container. I want to be logged into different accounts of the same service, in Brave I had different "profiles" for this, but I like that now in Firefox I can have everything in a single window and I can easily switch between containers by switching to a different panel. (Which I have a hotkey for)