I think I answered you elsewhere but I'll put this here: there is a 500,000 sat upper limit on transactions.
This is mostly because above this value I find the Lightning network to be somewhat unreliable and allowing for much larger transactions means I have to hold very large amounts of BTC on my Lightning node. Already I have somewhere around 0.5 BTC on my Lightning node to service the current level of transactions.
@v4vapp is not meant to replace big exchanges, it's meant for paying small bills for real services like eSims or credit cards or paying for hosting from @privex.
Thanks for the explanation Brian!