related but not really. It's more an issue with the browsers themselves than nostr but related because nostr needs those connections open for outbox.
created this test file: https://wip.alphaama.com/ma/ws_test.html
my results are Safari and Chrome load most (except dead ones), Chromium is hit or miss, depends if I have multiple windows using connections already I think, Brave doesn't open more than 28 connections on my system.
if you want to test in your browsers and post the results would be great!