No advantage over, say, ext4. I mentioned it because it is a good filesystem and bazzite chooses it by default so you probably have it. Also it has the best name.

You can check if compression if enabled by checking the contents of the fstab file (cat /etc/fstab in the terminal). It will say something like compression=zstd. It will likely be enabled.

There is no disadvantage to having compression on. These compression algorithms are designed to be used on the fly and are very fast. The overhead on a mildly modern system is imperceptible.

Whether you get mileage out of it is another matter. At a previous job I saw 20% reduced space usage on a postgres machine. On my laptop however the same stat is just 1%. It depends on the kinds of files you have.

Compressing something already compressed is pointless. So like emails or source code compress well, but video, audio or game assets do not at all basically. So doesn't matter for those things whether you have it enabled, and the overall percentage of uncompressed stuff on your drive is probably rather low, and mostly very small files.

I think the CPU overhead should be very small, but I haven't tried it myself. Plus if you actually have something that compresses well, it should actually be faster to access because you're almost certainly not CPU-limited, but rather limited by the read/write speed of the disk.