Never heard of the fact they gave glass bottles haha, my bad with the wording. I checked and we don't have an app for starbucks in order to collect those points.

Never heard of it, I'm in EU so probably that promo is not available here, can you give me a link?

Honestly just used a "shaker" which is a stainless steel one that I drink my protein with. Smells like stainless steel and tastes like one although it's marked as "non-bad-smell retainer".

Will the quality improve if I buy a specifically made bottle for beverages?

First time hearing about titanium ones, just searched but don't see any of that kind in my country.

I'm Southeast EU.