String quality?

[Koki]

I had GHS boomers (nickelplated steel) on my bass for 6 months and then the g string broke. Then I bought fenders (also nickelplated steel) and the g string broke in less than 2 weeks. I was slapping/popping both of the sets the same way.
I know that there is difference in string quality between GHS and fender but is it possible that the difference is so big?

[Baryonyx]

if I were you I would check out the saddle of the G string. Often, sharp saddles can cause a string to snap.