Most people who dislike cloudflare do so for their centralization of the internet, rightly so.
Me? I HATE THE STUPID "VERIFYING YOUR REQUEST" PROMPTS. THEY TAKE WAYYY TOO LONG AND DONT WORK WITH MY USER AGENT SWITCHER. STUPID WEBSITES WITH 3 MONTHLY USERS ARE TURNING ON ADVANCED "DDOS PROTECTION" JUST TO MAKE EVERY FUNCTION OF THEIR APP TAKE 18 MONTHS
The way ActivityPub federation works, once an instance is "linked" (like lemm.ee linking with lemmy.world, lemdro.id, etc), the instance will now send them an event once a post is made or something like that.
For example:
So yes, every Lemmy instance stores copies of new data from other instances once they link.