Game version: 1.20.1
NeoForge version: 47.1.104
Quark version: 4.0-460
Zeta version: 1.0-24

In TFC you get glass by using basin pour, which creates glass formed as block in world, and break it using Gem saw. After installing quark I switched off Glass shards, and it stops drop anything even with gem saw. If you enable shards you just get shards.

This is caused by both mods outright replacing Minecraft's glass loot tables (and Quark being loaded later): https://github.com/VazkiiMods/Quark/tree/master/src/main/resources/data/minecraft/loot_tables/blocks
and
https://github.com/TerraFirmaCraft/TerraFirmaCraft/tree/1.20.x/src/main/resources/data/minecraft/loot_tables/blocks
(Dev note: There are more compatible ways to achieve this now, so we should change it at some point)

You could make a datapack that contains copies of the TFC tables and that should replace the Quark behavior with the TFC behavior.