I'm glad that your two vaccine-related episodes of SCLS ended without the need for your hospitalization!
I have received four doses of the same vaccine (Moderna), and yet in late December I had Covid and the infection triggered an episode of SCLS, so at least in my case, sticking to the same vaccine (and thus technology) did not prevent a Covid-induced capillary leak.
Here in the United States, the official recommendation has been to persevere with the same brand of vaccine -- in fact, if you received Pfizer or Moderna the first time, chances are you were not even given the opportunity to switch brands the following times, so I'm pretty sure my experience is typical.
I believe that in North America and Europe, most patients have received the same brand/technology of vaccine over and over again, as well. Therefore, I doubt that your hypothesis is a valid one.
The hypothesis for which there is growing evidence is that if you are a duly diagnosed patient with SCLS, receiving any vaccine, or contracting Covid, in the final days of your IVIG infusion cycle, or when you have not received any IVIG on a regular basis, increases the probability of having an episode of SCLS.