Last I read, thereās no way to see how many devices have been connected. At this time, anyway. The only way Iāve seen mentioned is that when you notice your BAT on a newer device wonāt direct dump into your Uphold, itās because youāve surpassed the limit of four. Someone may correct me on this, if Iām mistaken. Maybe Support could determine this, but it seems it would be too much of a hassle for them to do this for so many.
No, this does not ālog offā it just disconnects it till you reconnect or not, but it will still take up one slot. This is why I think there may have been a miscommunication between that user who spoke to a rep at Uphold about ālogging off the deviceā.
Oftentimes, when a user is having issues with BAT transferring into their wallet, Support and others will suggest you to try disconnecting and reconnecting the wallet, but it remains whether you use it or not.
But, I noticed that it generated a new card in my Uphold account the few times I did this - I believe itās because I custom named my card(s). Iāve personally not had any issues dealing with Uphold, or when using their services, so far, but there are some aspects to them that seem touchy to me, so I try not to experiment on that site more than I need to. These extra generated BAT cards are an example of ātouchinessā for me: I canāt find a way to delete the extras and thereās no way I can determine which one is actually connected to my Brave browser because when I look in Uphold, I see one has the BAT amount⦠but if I click on withdraw through the Brave browser, it auto opens in Uphold to another BAT card that was generated, and without the balance⦠so I walk around it quietly for now and hope for no further mix ups 
Edit: The cards in Uphold are not the same as wallets⦠if this were the case, I donāt think Support would suggest dis-/reconnecting the wallet, because I canāt be the only one who customises things⦠at least, I hope this is the case 
Edit2: One last thing, if youāre into using multiple profiles in a browser⦠the wallets on each profile will count toward that limit, tooā¦