Why Is There a Bulge on My Pint Glass?

It's probably a nonic pint glass. Each nonic (or "no nick") glass has a carefully placed bump that makes them easy to hold and stack.

An Incomplete History of the Nonik Glass — Casket Beer

Everything You Need to Know About Pint Glasses

The return of the dimpled pint glass - BBC News

Authentic British Imperial Half Pint Nonic Beer Glass with Etched Crown Seal - 10 oz

How Different Beer Glasses Impact Drinking Experience

Choosing the Right Beer Glass Types (+What to Use Them For) - Savored Sips

Best Beer Glasses: Top 7 Types Most Recommended By Experts - Study Finds

Acopa 16 oz. English Pub / Nonic Glass - 12/Case

Drinking Glasses Guide : r/coolguides