Hello everyone. I'm pleasantly surprised at everyone who took the time to think through my experimental issue, and I do have an update. I believe the problem was a rather gross oversight in my apparatus, but first, a quick description of my apparatus. I used an inverted 500mL erlenmeyer flask for the collection of the gas. I know that this isn't the most precise instrument, but for the theoretical gas yield its the most convenient. To measure volume, I mark the bottom of the meniscus whenever the reaction has stopped, i.e., there isn't a seashell in the reaction flask, and shaking releases no further gas. I then fill the erlenmeyer up with water to the mark I previously made, and measure using a graduated cylinder in intervals of 100 milliliters.
I'm pretty sure that the misstep in my apparatus was having the tube near the top of the inverted erlenmeyer. With this setup, once some gas has been produced, and the end of the tube is no longer submerged under water, the pocket will suck in more air to displace the water due to gravity, in the event a leak. I spent around 3-4 hours today simply toying with my apparatus, running many simple baking soda and vinegar reactions, since they are both abundant, release CO2 gas, and the reaction happens much faster. If there were to be a leak, the gas in the erlenmeyer would be significantly made up of air that was sucked into the pocket to alleviate the potential energy of the water.
To solve this, I connected a two-holed rubber stopper to the bottom of the inverted erlenmeyer, with one of the holes connected to the tube that leads to the reaction vessel. With a small glass tube entering the inverted erlenmeyer, The tube is always going to remain under water, meaning that if there were a leak, say in the tube or at the rubber stopper of the reaction flask, then the reaction gas would be lost, rather than air being sucked into my inverted erlenmeyer. Doing this, I found my yield to be lower than expected on some trials, which is much better than a 250% yield, and easier to explain. An image of my apparatus has been attached below. It's just a simple apparatus set up in my bathroom.
It is still rather confusing though, since when I did the experiment, it would take at least an hour for bubbles to even form in the inverted erlenmeyer. My guess was that pressure needed to build in order to counteract the pressure of the water in the tube, although the atmospheric pressure in the reaction flask should be the same as the water. Upon shaking the reaction vessel, the gas in the tube would move along slightly, until eventually, it released into the inverted erlenmeyer, which would chain the releasing of what I assumed to be the pressurized CO2 formed from the reaction. If anything here sounds incorrect, I'd like to hear.
Aside from that, thank you to everyone for giving my some insight, especially with the CO2 being dissolved in the vinegar and water explanation. This was something I completely overlooked, and would help very much in explaining the decreased yield of gas.