Photosynthesis and gas exchange are primary functions of those fan leaves and it could be now that you are supplementing co2 you may need more of that leaf surface to get the job done
We can all see on our plants the different sizes of fan leaves. Some are the size of a small kids hands and others the size of a sheet of paper. After a certain size ill pop off those huge leaves as the other 50 smaller fan leaves will get the job done for photosynthesis.
Ive had plants that did not have any big fans but the stems would just look hairy from all the slinder leaves sticking out on em.
When growing bigger plants vs tiny plants those big fans are not necessarily as important.
Another thing is if the plant needs more leaves it will grow them out.
I started plucking big fans off years ago. I had bought some neem oil and followed the directions on the bottle in mixing it. I sprayed it on some gorilla plants outside in the woods. Those plants where 10-15 foot tall. Burned off all the leaves off the plants. Thought i killed em all trying to get rid of pests and havent used it since.
Those plants grew out more leaves and they produced a lot of bud. I had to Stay on top of things because they did not have any nutrition left in those fan leaves in case they did not have enough fertilizer to supply enough nutrients for the Bud development. From then on I started plucking leaves in my greenhouse and plants that were closer to home that I took care of more regularly. That had to be 20 years ago.
Since then i have grown thousands and thousands of plants and always used the practice of taking off big fans when they are not necessary.