Good questions xd @justsomeone1 . Before writing this i began to research in all posible places with info related to slots on uphold. And just to avoid giving a bad answer i did this with the mentality of a new user. What i found is this:
Lifetime slots on uphold depend on your browser wallet.
Before the actual situation we could get our wallet seed phrase, and with that we could use it to recover only pending rewards (since 1.3v) but also to avoid uphold lifetime limit. What really counts are not devices, but wallets.
So if in a year i needed to format and reinstall an O.S. in my computer, lets say 4 times, and then i installed brave and recover my wallet. Then if i connected uphold on those 4 times it will only count as 1 slot not 4, this because i´m using the same wallet. So with this i can say i had a wrong idea (sorry for that).
In other case let´s say i didn´t recover my wallet and began all those 4 times with a new one, then the 4 slots were going to be wasted.
So the correct statement is we have a 4 lifetime wallet limit. But:
Actually the function of getting your wallet seed phrase is disable (due to wrong conception on recovering earnings since 1.3v like you can read on my past comment), so with this is correct to say that we have a 4 lifetime device limit, this since the common user scenario is installing brave once per device. So said that, with a new install comes a new wallet and with that a new slot to waste if you connect to uphold (if you are a new user and/or you don´t have seed phrase). And well the same applies to mobile.
I know this sounds unfair, for now, but the actual efforts are to use syncv2 to sync this wallet data, so this can be a solution, not only to recover earnings and pending rewards but to also avoid lifetime limit.
As for @Steven_Smith question, well, we can only wait until syncV2 is improved and adds this feature
Sources:
https://www.reddit.com/r/BATProject/comments/hckpou/does_recoveringrestoring_an_existing_wallet/