I'm not saying. But I'm just sayin.

Probably the frequency of changes- more and more memes- than anything nefarious.

https://web.archive.org/web/20220000000000*/imgflip.com Look at the activity as it shows a heatmap on timeline in which it shows how often and what is being archived. They also archive just specific pages (apparently)

What do you think are possible reasons? Is someone preserving evidence?

Possibly. Think about it, you have a website that is spreading memes that endorse the Big Lie where children have access. DARPA is researching (and has been) the efficacy in the use of memes as propaganda. It is known that this site permits 13 year olds to be here. So... That is worth noting. Again, I'm not saying, but I'm just saying. I'm pretty sure FBI knows about this place.

I hope they do. Prior to 1/6 I noticed a few comments that in retrospect suggest to me a few people here might've been involved.