I tried Zabbix 5.4 clean installs in 3 VMs. 2 Centos 8, 1 Ubuntu 20 and there is a problem with Graph Widget.

No matter what interval you use, it is not updating, the widget does not get refreshed unless you reload the page manually.

For example, create a simple Host with a Web Scenario and monitor a URL.

Although in Monitor > Hosts > Web Scenarios the graph is updating and showing fine, in Dashboard when you add the Graph Widget and select from the host, response time with interval 10sec and save it, the widget is not getting updated, it doesn't scroll through time.

If you select Widget Classic it works just fine. Also in 5.2 version it was working also fine the Graph Widget.

I found out that when you set -> Set custom time period in the widget (now-5m now) then the widget's timeline starts to work and move normally, but only if you set it in the widget's custom time period. If you leave it unchecked and use the dashboard time period, it does not work.