Selfhosted on Hetnzer with Docker Compose (slow backend respond)

Currently, my website: https://iam.mingshun.me is running on Hetnzer ARM64 with several services, namely: Nginx Proxy Manager, Uptime Kuma, Portainer, and 2 Ghost containers.
The result on GTMatrix highlighted that the website response on Backend TTFB is almost up to 0.8s!

I would like to know whether there are any tweaks to reduce in the backend TTFB without a hardware upgrade?

Additional: docker stats looks like CPU and MEM USAGE aren’t the bottleneck of the issue.