Applications not using system wide theming

A day before the creation of this topic my system underwent an updation (a huge one) and a lot of applications along with the system updates were done.
But after the update, I noticed many applications stopped following the system-wide themeing ( telegram desktop, gnome-clocks, etc). I tried checking if my themeing had reverted to default but I noticed they were still the same. Also, I only happen to notice these changes in gtk-based application themeing.
So what should I do to get back my old system-wide themeing?