I'm not a developer so take this with a grain of salt, but this may help: https://medium.com/hypersphere-codes/detecting-system-theme-in-javascript-css-react-f6b961916d48
I'm guessing you do a bit of content caching to smooth how things load for the user? I don't see the usual chaotic load of most clients, that's great.
If you want to diversify from the large relays, you're also welcome to add my relay: wss://n.ok0.org - it's spam free at the moment and has some basic filtering in place.