Data remains at the date level, and the month (here, April 2023) gets repeated on every single line. Same will apply to line charts, bar charts, ...
How can this be fixed? Well, we'll have to pre-aggregate in the Blended data directly.
Aggregating by week or month directly in the blended data
Please Edit your blended data, remove the date dimension, click Add dimension, and create a new one with the level of granularity you're looking for. In our case, we'll go for month, but same would apply to week, for instance writing something like: