I noticed this tool while travelling and it threw me slightly for a while.
In the below screenshot the total spent today is displaying transactions made yesterday.
But I realised that the timezone for the summary bar is probably fixed because it shares the timezone with the pulse graph (which I have to wait another month to access 
) & it’s timezone is fixed as UTC. I’m guessing that the reporting (CSV exports / Monzo’s transaction log database) is too.
If it wasn’t, then tracking which day your transactions were made could become pretty confusing as transactions that were made at 11pm EDT Monday will switch to 4am Tuesday in Pulse & reporting, when your timezone changes to UDT.
So I actually prefer the total being out of sync with my current timezone when I’m not in UTC - you know where the transactions will fall when you review your monthly spending back in UTC, it’s just something that you have to bear in mind. Maybe that’s just me though 