That’s not a issue, but feature. Grafana is trying to use the best aggregation for your resolution.
For example for 30days:
1h resolution for 1k monitor = 30x24x1= 720 points
15min resolution for 4k monitor =30x24x4= 2880 points
It won’t make sense to render 2880 points on 1k monitor, but it make sense on 4k. That is magic which is calculated based on resolution and selected time range, see doc for $_interval variable