What happened to my Internet speed?

Lately pages are loading much slower. I especially notice it on YouTube, I’ll scroll down the main page and the static images for the videos are blank and the spinney progress thing is spinning I click the notification bell and once again it just spins (because that little notification box takes so much bandwith)…same thing for images on Pinterest.

Now is it just a coincidence that AT&T is putting fiber lines up in my neighborhood? Am I supposed to complain and their response you need to upgrade to our new high speed fiber for an additional amount?