Can I use Clorox Bleach Gel on my Karbala tile grout?

I've used it on my shower grout, but at 50% strength. Meaning, I diluted the bleach with 50% water.

I can’t find the brand name of your tiles.

If they are marble, marble is very soft and chemically etches quite easily.

I would not use chlorine bleach on any grout, because it is hard to rinse off.

I would use an old toothbrush with the neck bent so the head is perpendicular and very mild soapy water.

In the long term, I would dye the grout a dark color.

I would be careful using bleach! I would use Young Living's Thieves cleaner to clean the grout. We use it for every surface in our house--works great