I’d try keeping requests to a minimum, like with putting everything to download and watching those instead (e.g. with yt-dlp or Grayjay’s Watch Later playlist set to auto-download), using RSS on another device/IP (e.g. with a VPS, @birb@rss-parrot.net on Mastodon or a phone/Raspberry Pi on another connection) then forwarding over to your main device, avoiding requesting all subscriptions in a row (e.g. Grayjay’s Subscription tab or having a too aggressive refresh/fetch setting on an RSS reader), rebooting your phone when issues start (if it’s a cache/memory leak issue), and/or using a VPN and changing servers as needed.