Well, this pattern of thinking is a fundamental error that many beginners make. This probably happens when they read posts on Klingon websites and it programs them into this pattern where pearling becomes the overriding feature of a tank. When you become a more advanced plant grower, I promise that you will actually consider pearling to be a total nuisance. At this point, for you, it's a novelty, so I completely understand that it's a bit of a disappointment if the pearling disappears.
As it turns out, the phenomenon of pearling is actually the result of several parameters involving CO2, light, nutrients, water temperature, ambient barometric pressure, as well as the solubility constant of the gas. So it's possible to observe pearling under a wide variety of conditions.
During the photoperiod, photosynthesis occurs regardless of whether the oxygen bubbles are present or not. At lower photosynthetic rates of production, and depending on the water conditions, the Oxygen simply dissolves into the water and that's why you cannot observe a bubble formation. At high production rates, the solubility of the gas competes with the gas buildup rate. Oxygen is not very soluble in water, so the ejected gas does not have time to dissolve completely and the excess gas escapes immediately into atmosphere.
Therefore it is never an ON or OFF issue. It is only a matter of degree and the effect of the present environmental parameters. In you case, all the other parameters have been held constant but the light energy has been reduced, so the rate at which Oxygen is being produced is also reduced. This allows the gas to more easily dissolve into the water, so there is no bubble formation.
Oxygen is produced as a waste product by a protein called (unsurprisingly) The Oxygen Evolving Complex (OEC). This system of proteins remove the Hydrogen from H2O. You may remember this being called "hydrolysis" in high school lab. The positively charged Hydrogen ions are sent to a holding area. It is the Hydrogen ions (H+) that are needed because they are used in a very important energy producing process. The Oxygen atoms then combine to form "O2" and is released at the underside of the leaf.
So whether you see them or not is irrelevant. The most important visual indicator is the health of the plant and the absence or presence of algae. The bubbles are simply a matter of degree, not an all-or-nothing indicator.
Cheers,