Aspect ratio problems

Hey everyone! I’ve been using instagram for fun for many years. I’ve always posted my art and what not. Recently I took a hiatus, I left in September but now I’m back.

For my account I need to post things in a mosaic/puzzle feed. I usually always do a row of 3 posts. I’ve figured I can create it by setting my art canvas (in procreate) to 6000x2000 px and then use a panorama crop app to cut it.

But the problem is now with the new ratio I’ve tried dividing the posts in 4:5 and 3:4 ratio but the posts are still not lined up. And the canvas sizes I’ve used are 3240x1350 and 2160x1132 and neither of them has worked.

I don’t really know how to change my account’s feed, because some posts will be an individual photo and others are banners (3 posts in a row). I’m doing a kind of metaverse Kpop group and so there’s like a specific way that you post things. And I’ve asked some of the people in my community and we’re all having the same problem.

I know im late to the party, but just so confused an angry as to why they changed the aspect ratio in the first place.