In version 4.0.16, charts are being trimmed when selecting a longer period.
In the prints below (1,2,3), zabbix is at version 4.0.16 and graphics are cropped for a long time even if "Now" is selected.

And in the prints (4,5,6) zabbix is at version 4.0.15 and, as a longer timeframe selected, continues to appear at the current value.

We have downgraded the zabbix-web- * package and the issue has been resolved.