Social network Reddit recently began blocking mobile visitors to its website while pushing them to download the official Reddit app, and it's fair to say that the move is not going down well with users. If you visit reddit.com on your iPhone today, you may see a new popup that can't be dismissed, asking you to "get the app to keep using Reddit".
old.reddit.comis unaffectedThe few times I click a link to a Reddit post I immediately change www to old. That new monstrosity is unusable.
Try https://addons.mozilla.org/en-US/firefox/addon/old-reddit-redirect/
For more general usage, you can try Redirector.
You just add a rule like
Redirect: https://www.reddit.com/*
To: https://old.reddit.com/$1
It allows to redirect to alternative frontends, and redirect other webs like YouTube too :)