The Gaviscon Advance Liquid that I purchased (I got 3 bottles) was fine, sealed, etc. and works well. I still see it on Amazon:

https://www.amazon.com/gp/product/B002AKA9O0/ref=ppx_od_dt_b_asin_title_s00?ie=UTF8&psc=1

Reflux Gourmet has the same algoinate the Gaviscon Advance liquid has (the mechanism is that it hits the stomach and forms a layer on top of everything to hinder stuff from coming up into the esophogus.

https://www.amazon.com/gp/product/B086ZYPWQK/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

I'm in a bit of a panic on the tablets: I have some here at my desk at work and keep them on the bedside table. I went to the link where I purchased my 6 pack, and they don't recommend sellers, but my Fakespot addon recommends a seller but the 6 pack is $100. I paid $82 when I last ordered. I'm going to run the experiment and order and I'll report back.