A simple animation increases my rendering time up to 8 hours

Hi, I'm editing a podcast (4k, 25-30fps) and I would like to add an animation where the logo of our Project fades into the logo of the show and vice versa (both logos being at 85% opacity). Everything goes smoothly, I finish editing without any crashes, and then when I start rendering (either through Premiere or Media Encoder), it tells me 'Estimated time: 8 HOURS'. How can a simple animation of 2 PNGs cause rendering issues??

How you can see in the picture, I'm using the animation as .mov because I thought that a

video animation would help me (before it was a subsequence), but the fact that even with this simple animation (8 minutes just changing the logos) it took 30 minutes to render...