Segmenting by custom dimension in 3.13.X


we updated to Matomo 3.13.X recently and noticed that the custom dimensions feature is working differently compared to 3.12.0.

We have 1 action scoped custom dimension and we are using simple segmentations to filter out custom dimension values.

When browsing to that custom dimension in the Matomo portal we see plenty of different values without segment selected. However when selecting a simple segment (eg. exact match), the result is still showing other results in addition to the exact match. Why is that? In <= 3.12.0 version it would only show the exact matched dimension value and nothing else.

Is it like this on purpose or is it a bug?