I have noticed that the Chrome Browser has changed the scroll bars. First, they got a lot smaller, so it was hard to see them. Next, they would disappear if it thought you didn't need them. This made it difficult to scroll down the conversations on the Home page.
I think I figured out the settings to "fix" this. Be aware that changes are at your own risk.
To change the "flags" used in the Chrome browser for the PC, open a new tab. In the address bar, type in chrome://flags and hit enter.
In the search flags field at the top, enter Tab Scrolling. It is probably set to Default. I changed it to Enabled - tabs don't shrink. This set the flag so the scroll bar is always visible and back to being big.