Hey again.
I think this has been an issue before and was fixed at some point since I've made similar projects before (successfully), but now when I try to export a video that is meant to play in a seamless loop, I get this/these black frame(s) at the end. So when I try to play it in a loop, it doesn't play smoothly anymore because of this.
What I use in my project is an image that is set to 30s, it uses the temperature and glow effect in the middle. No black frames set at the beginning or end of the sequence. Everything looks normal in the preview.