[TriLUG] tab completion behavior changes with recent Ubuntu

[Pete Soper via TriLUG]

Running Ubuntu 18.04.1 with recent updates.

I type this:

/cp $HOME/Pictures//

Then I type "tab", expecting this, as I would see for the last decade or 
two:

/cp $HOME/Pictures/20200921_STM32F031F6P6.jpg/

But instead I see:

/cp \$HOME/Pictures/20200921_STM32F031F6P6.jpg/

So then if I've forgotten the freebee backslash, when I add a period to 
get the file into my current directory:

/cp \$HOME/Pictures/20200921_STM32F031F6P6.jpg ./

Instead the operation fails as HOME/Pictures isn't valid.

What is causing this and how to I eliminate?

And out of curiosity, how did I accidentally enable this free escape of 
'$'? Is it a feature somehow?

Thanks,
Pete