Beside @solene’s valid point, I could add the default template is f38-minimal which is 748MB. Still big? Well, the thing that helps the most with saving SSD is if you use zram swap, if I’m asked.
But, as I may, Qubes’ choices shouldn’t be based on this characteristics, just like I’m sure one day someone in the know enough will contribute with Alpine template too.
To me, it just looks that it isn’t important almost at all which template you use until you use qubes based strictly on your threat model aligned with Qubes philosophy. And default templates (the ones found in repos) are more than enough for that.