What you are describing is precisely the symptom of needing a new flapper.
Change the flapper and see if it fixes it. Assuming that that's a Drake or other Toto GMax toilet, then use this one:
https://www.korky.com/products/flapper-seal-replacements/fits-toto-g-max-3-flapper
Also check the overflow tube (the thing that rises up on the flush valve). Sometimes it cracks vertically, often behind the clip that attaches the refill hose. Turn the water off and see where it settles to. If it settles all the way down to the base of the flapper, it's the flapper. If it settles say halfway down and goes no further than that no matter how long you leave it sitting, then unclip the refill hose and pinch the overflow tube and see if it doesn't reveal a crack/separation.
But I wouldn't go there until I changed the flapper. It's cheap, easy to do, and can't hurt, because you're gonna need to replace it someday anyway. Count the links of chain between the flapper and the flush handle on your old flapper, and duplicate that on the new one to start. Flush it, and see if the flapper acts properly. If it doesn't stay open long enough or closes to soon, play with the links of chain one or two in each direction until it works perfectly, which it will if you are patient and try different lengths. Generally, you want one link of chain resting on top of the flapper when the handle is at rest, i.e. a smidge of slack in the chain, but you then vary the lengths until you get the flapper to work right when you flush.
In the future, if you replaced the fill valve with a Korky 528 of any flavor (or that's what it came from the factory with), all you need to replace to solve the noise problem you were experiencing is the little internal seal, which costs like $4 at Home Depot. You don't have to take out the whole old valve. But if you replaced the valve yourself, great! Good DIY project.
Good luck. Let us know how it works out.