The point of using a diffuser with an ozonator when ozonating liquids is to have the ozone make contact with as many molecules of the liquid as possible in the shortest time possible. By creating many small bubbles, contact is far better than a few large bubbles. Cheap bubblers will decompose with ozone but usually not quickly.
I'm doing a test right now but with a medical grade ozonator fed with pure oxygen from a concentrator. The RO water I started with was 1 ppm with a TDS meter. I'll let you know if it changes. I suspect it will not.
What I think may be happening with your change in ppm is that possibly if the ozonator is an air-fed unit with no air dryer, and the air in your area is fairly humid, that the increase in ppm after ozonating the water is due to the NOX created by the machine in these conditions.These are nitrogen compounds created from the 60% nitrogen in room air by the same process as ozone is produced when moist room air is used for the process.I doubt if it's your bubbler.
I've been ozonating my water for eight minutes now and there is no change in the ppm level of dissolved solids.
Hope this helps