Rather than domains, your screenshot shows failing resources, i.e. something served by a webserver for the domain you are accessing, which seems to be www.steadyrack.com.
For me, acccessing that site produces only two DNS requests, one for www.steadyrack.com and one for cdn.shopify.com.
The page is loading fast, though uBO is blocking some stuff in my case:
Since your screenshot demonstrates that www.steadyrack.com has already been successfully resolved (or else you'd not see any content served by that site), how do you suspect Pi-hole to be involved here?
There's certainly a possibility that it isn't. At least some of the resources which are taking excessive time and seem to be slowing down page load are all served by domains on Pi-hole block lists. I had already disabled ad blocking for that site to try to troubleshoot. There are no issues when disconnected from wifi so I know it's something on the network. Your comment made me realize that my Unifi gateway is attempting to do ad blocking as well so I've disabled that to test.