I am sure that they do not consider it to be lying - in the same way that calling a death from a fall after a heart attack either death from a fall or a death from a heart attack would both be true, and both be misleading.
The usual practice is to record both the immediate cause of death as well as other contributing factors, with the understanding that it is often not possible to ascertain which is primary at the moment of death. So most death certificates contain multiple causes.
You say that this is "misleading", which implies that those who record the death are misinforming others. A better term would be "
misunderstood", that is, the general public who read a death certificate are often unaware of the reasons for including multiple contributing factors, and some of them may mistakenly suspect that it is something that suddenly appeared in covid times. It's been done like that for a century or so.