Files from my domain are being served with various "X-Powered-By" headers

When I scroll through all the requested files when I visit my home page, a lot of the css/js files give me different results in the X-Powered-By header. Been running EE4 for a while now, upgraded to latest version the night it was released. I’ve tested on other sites hosted on my server, on those other sites all headers on them show 4.0.9 – it’s just this 1 specific site that has varying headers. I’ve purged the server cache, browser cache, loaded the site in multiple browsers, the issue is all there. But again, just on this 1 specific domain. WordPress is up to date. Only WooCommerce and a basic theme is installed (plus nginx-helper and the redis drop-in)