Aha! Nice spot
Don’t worry and you don’t need to tweak your budget any more.
It looks like the latest update may have introduced a small bug in the track process (possibly only on the latest version which is out for Android but not yet for iOS). It is not that the budget has been lost, but rather that the daily spending limit for the final week of the budget shows £0.00 per day for some reason.
In your case, since this is the last full week of your budget, the days are all showing the £0.00 available per day. If someone else has a budget for the end of the month, it is only the last two days of April that will show £0.
I have raised this with the team and will investigate. Thanks so much for raising it!