Hi,
Looking through the source I found
public/app/features/dashboard/containers/DashboardPage.tsx
if (!prevProps.dashboard) {
document.title = dashboard.title + ’ - Grafana’;
Change the ‘- Grafana’ value and the title will be your custom title.
There is also the public/app/core/config.ts -> windowTitlePrefix: 'Grafana - ', but that does not change it everywhere.