Help - Toto Toilet wasting water? (VIDEO included!)

I have a Toto toilet that is working well, however over the past year, I have noticed it has been making a constant sound. (Almost like a recharging sound?) Also, when I flush it, it doesn't seem to refill at once, but in two-second increments that is, quite frankly, very annoying. I've also noticed a pretty dramatic increase in our water bill (almost $100 a month more) and I don't believe I have a leak elsewhere in the house. Do you think this could be the cause?

I've recorded a video of both the constant sound and the flush routine - check it out:
https://youtu.be/ufOj3Ka9-0c

I'm not much of a plumbing guru, so any help is most appreciated! Any idea if this is abnormal and what parts should be replaced? Thanks!

Replace the fill valve.

Yep!!

Replace the fill valve

get a water test gauge and check the water pressure.

Thanks to both of you. I was able to find a replacement fill valve cap for $6, and by following the instructions on a YouTube video, it was super easy to fix. Now the water replenishes at one time, and I don't hear the leaking anymore. Appreciate it!