All plugins are green, though being outdated!

Hello,

I’m using WordPress 4.7.3

I used to update the plugins from time to time manually. Since the beginning of this year 2017, I noticed that plugins are always remarked with the green status as updated, and then no update messages appear to me as before. I discovered that most of plugins now are outdated!! Though, it still show it is updated!!!

Any help?

Thanks…