Liquid gel builder/overlay

So I will preface this by saying I’m not the most knowledgeable about different options beyond gel, dip, gel-x.

I went to a new salon today to get gel builder, and they ended up using a liquid base. I have only ever gotten the gel builder where the tech squeezed it out of a tube and shaped it to my nail, so I’m confused what the liquid base was. This tech told me that she used a “gel base” instead of “gel builder” because my naturals nails were pretty thin/brittle. I unfortunately didn’t get to see the bottle too well, but it looked like a clear liquid base. The whole process was basically done like a gel manicure, but they charged me the amount of a gel builder process.

With that said, does it sound like they just did a gel and upcharged me? I don’t mind paying for quality work, but I’m not sure why I would pay for a more expensive treatment if they didn’t have to do the shaping.