Rouge (buggy) bot, (D)DoS attack (maybe intentional, maybe accidental). Maybe you are reading the numbers wrong. Maybe you or your website became very popular.

Check your access logs.

Without sharing access logs people would just be guessing. Even with logs there may be some guessing depending on what information is logged.

We've been getting hammered by bots. Some declare what they are, many hide it. It's been a game of whack-a-mole on Cloudflare to block them. Essentially hammering the site so hard it's a DDOS. Brazil, Singapore, Vietnam, Chile, all over the place. Single datacenter IP's just scouring the entire site, non human traffic.