Although Glass Bottles can be funneled into Brewing Stands via Hoppers in both Java and Bedrock, on Java it can only put one in each slot, whereas on Bedrock, it can put up to 64 in each slot.
How to reproduce:
1. Connect a Hopper to the side of a Brewing Stand
2. Place 4 or more Glass Bottles in the Hopper
Expected Result:
Three of the Glass Bottles get funneled into the Brewing Stand, and the rest remain in the Hopper
Observed Result:
The Hopper is able to put multiple Glass Bottles in the same slot.
Can confirm!
Although I wouldn't say that the expected result is that 3 glass bottles should get put onto the brewing stand. Empty glass bottles should not be able to be placed on the brewing stand at all. Only bottles filled with water or other base potions. And those do not stack.