Wordpress site / VPS issue

Job ID: 33850522

Budget: $30 – $50 USD

The client has a WordPress website with about 15.000 visitors per day. Since 3-4 months ago we set the new website. After that, almost on a daily basis, they have issues.
The server is 12 CPU Cores with 32 GB of ram. We are using Cloudflare pro.
Dashboard - it starts working slowly. It takes them for making ga post about 5 mins
A couple of times a day they got Cloudflare error 524
In the terminal, we notice large CPU loading
We need to find an expert who can detect what is causing these issues. Is this DDoS, some plugin, or something else we need to resolve asap. We have a VPS with 50.000 users per day and it works perfectly so there is something wrong with this one (I think something with the plugins or some config of the WP).
We need a Server / WordPress expert who can resolve this asap so that admins can use it normally and can add the posts fast and quickly.
Related categories: Linux WordPress MySQL Web Hosting Server