Yes, Raoul, Betelgeuse does regularily expand and contract.
But this latest data is different. Vive la difference!
This latest data, over the last 15 years, shows continuous shrinkage, 15 percent, that is accelerating not slowing down.
I suspect Betelgeuse has burned through most of its hydrogen,
helium and carbon.

And get this! A red-giant star's last three element-burning/fusing phases
last about 16 years.

I got the following info from Wikipedia.com

12 years to convert its neon to oxygen and magnesium.
4 years to convert its oxygen to sulfur. Silicon is there somewhere too.
And one week to convert the final slew of these light elements to iron.
Then the final collapse begins.

That's 16 years more or less! And this latest astronomy data
on Betelgeuse shows definitive major continuous shrinkage
for 15 years! Coincidence? I don't think so.

I feel with more than 50 percent confidence that within the
next 14 months Betelgeuse will be seen as a supernova in the
sky, much brighter than the full-moon for a few days or weeks.
Except for the dreaded electro-magnetic pulse that might
fry this computer from such an event, I - am - excited!

HEY! In the last 15 years we saw comet fragments strike Jupiter,
and have seen 3 exceptional comets brighten the sky.
Now it looks like we are getting our first naked-eye Milky Way galaxy
supernova since 1604.

I can hardly wait!