Grafana 'Join by Time' removes null values?

I’m noticing if you have multiple metrics on a panel and go to inspect > Data and toggle the ‘Join by Time’ prior to hitting the ‘Download CSV’ button, if any of the metrics have null data for a specific time, then all the other metrics will also not have that time when downloading. It essentially finds only times that all metrics have a value for… Is this intended? Previously, before Grafana 7, if you downloaded data and something was null it would just be a null value in the resulting CSV.