Why my rendering slows down and stops at an arbitrary frame?

When I’ve tried to render an animation, the first frame seems to take way longer than it usually does. Then, I return a few hours later, and it seems to have stopped at frame 26 or 31, when usually the render would’ve been finished under normal circumstances.

I’m using the EEVEE engine with all of the render settings how I usually have them, outputting to ffmpeg mp4, perceptually lossless, with the default sampling settings. The animation is 400 frames long and all the physics have been baked.
One thing to note, before rendering in EEVEE, I tried to render the animation in cycles before realizing it was taking too long, so I canceled the render and tried to render it again in EEVEE, changing all the appropriate output settings accordingly. In the past I’ve rendered a few animations in EEVEE without ever having this issue.