Not exactly what I described here, but if I go to Subscriptions and then quickly before it loads I go to the All feed, then I see this, which is the titles and bodies of posts from my Subscriptions feed with icons and upvotes from the All feed.
At this point I'm not sure if what I described in my first comment happens at all, or I misremembered this as being that. If it ever does, I'll come back to you.
Oh, that's probably the app. So, the way Android does infinite scroll, it takes a lot of resources to create a "view" (the thing that holds the details of a post), so as you scroll, when a view goes off screen, it gets reused instead of destroying it and creating a new one. This is called a recycler view. When a view gets recycled, it is supposed to replace the details that are unique to each post (title, image, etc.) and keep any other detais (any text that might be common to all posts, any sub views like upvote and downvote, etc.). But if your logic isn't right, sometimes something might get kept instead of replaced when the view is recycled.
I remember making this mistake the first time I used a recycler view back when I was working on my senior project in college, many years ago now. I don't remember how I fixed it or the exact details around why it happened, but I know that I did fix it at one point.