My wife and I bought our house brand new a couple of years ago. Now I'm not an expert plumber nor do I claim to be (self proclaimed geek really

) but the old fashioned toilets made sense to me and I was able to repair a flapper or float ball when needed.
Recently the toilet in my master bathroom started running all the time. Pretty loud too. I took the top of the tank off and it apparently is a new type of mechanism I've never seen before (see photo). After listening with the tank open it sounds like it might just be air leaking instead of water running, or maybe a combination of both.
To me it sounds like it is running where I marked the red arrow in the photo. I really don't want to hire a plumber to fix something that probably is simple and could be done myself if I understood this mechanism or why its making this noise.
Does anyone have any ideas? They would be greatly appreciated! If I need to provide more info please let me know. Thank you!