I put that message as private. I do not know what really happened and no need for me to spend any effort find out. Even hacker come into my personal blog also not much use to them as inside my blog no money there. I also got maintain full backup daily weekly monthly on my remote storage. I monitor a while if will happen again.
Maybe my blog is running over 10 years, some inactive plugin is still there so I removed all of it as it was too old to prevent this happening. I running more copies of full backup on my website instead of a few just in case.
I using VPS, low cost using EURO to pay instead of USD is much cheaper due to conversion currency rate. Located under a local data center in https://contabo.com/