Size on disk double of actual size

Hi, I finally set up a proper nas with a pair of mirrored 4TB disk with a pair of SSDs as a Log VDEV, but I noticed that everything takes up about double the size of the actual files (I’d say double minus space saved by LZ4).
I also have a second share with mostly large (>1GB) files on the same pool, which also has that behavior, and another pool which doesn’t act like this.
I set up the pool yesterday, so there is only one snapshot, which shouldn’t be the cause.
Pretty much all the files have been directly moved form the other pool.

Thanks to anyone willing to help!

ElectricEel-24.10.1 running in a proxmox vm.

I wanted to attach screenshots of my settings, but the forum won’t let me for some reason.