Here is the section from the patch notes:
There are 4 tech levels of items in the game. These start appearing in loot at the following Game-Stage intervals.
- Tech 0 (GS 1-11) – Primitive tools, weapons and armor including a bow and the blunderbuss.
- Tech 1 (GS 12) – Iron or similar melee items and armor and and the first proper firearms like a pistol or double barrel shotgun.
- Tech 2 (GS 50) – The best melee items, bows and armor and mid range firearms like a pump-action shotgun.
- Tech 3 (GS 91) – The most advanced firearms like an M60 or the Sniper Rifle.
So as I read it for the first 11 GS you will only find Tech 0 items, but starting at GS 12 you will have a chance to find Tech 1 gear. A chance. You will still be finding mostly Tech 0 stuff for a few more GS levels, but Tech 1 will slowly become more common. I would guess that by about 10 GS levels into the Tech Tier you will be finding mostly items of that tech.
The question for me is at what point do the lower Tech items get phased out if at all? When you get your GS to 100 or more will you still be finding Tech 0/1 items or would they have dropped completely from the loot tables?
Take a look at the patch notes under
Dynamic Resolution
https://7daystodie.com/a19-official-release-notes/
That is probably the biggest change but there are also a lot of smaller things like improving the graphic images and skins to make them more resource friendly and less intensive for drawing.