Server Resource Quota

I've just got access to a customers Tenant and they have 1 site collection with 54 subsites.  I'm planning on sorting all that.

But I noticed that on the SharePoint Admin section, the Assigned Server Resource Quota was sitting at 41600/31700

I was wondering if anyone could give me any information on the impact of the resource quota being at this level?  I've found a few articles, one of which suggests that since "code-based sandboxed solutions have been blocked entirely in SharePoint Online from July 2016, this setting now does absolutely nothing at all."

If anyone has any more/better information that would be greatly appreciated.