I sometimes wonder if the change to the culture and ways of working from the covid-era WFH days became more pervasive than I realized.
It also can be that the office space itself is too noisy so any discussion can distract a lot of people.
I've found most work communication apps not to be very condusive to it, but Discord is pretty good.
I sincerely miss working in an office, but with my current job it would've been impossible anyway (everyone is remote in different countries). I've only once met some of my coworkers irl a few years ago when we went to a conference together.
You can see if people are in there and actively talking before you join and that alone encourages spontaneous drop ins.