Depends on where on the +100ms range we're on. Once you start hitting 1s latency, lots of applications (or rather, their servers) have a hard limit on 1s for every request. So when loading data from the backend, you have to continue to retry the request until it gets below 1s and then you will finally get the data.
I think Adobe been one of the worst companies I've dealt with personally, as many of the endpoints have ridiculously low timeouts (for someone with really shitty latency).
Anything that requires real-time interaction between a client and a server and other clients, e.g., gaming, stadia/geforce now, videoconferencing, ...
< 100ms is usually the "minimum", > 150ms is often "unusable", and for a smooth experience you might need < 30ms depending on the application (e.g. depending on the game you might need < 90ms or <60ms or <30ms).
Depends how much you care about people talking over one another. If your call is a presentation/lecture/class with few switches between speakers, latency's no problem.
But if your calls normally have lively discussion where someone different jumps in any time there's a pause, the higher the latency the more likely people will say "meeting in person is much better"
Likewise, with things like remote desktop, 100ms of latency isn't a dealbreaker but it'll certainly leave some of your users saying "things that run locally just feel snappier"
For mobile phone networks, >20ms latency in audio is "unacceptable" from the point-of-view of standards conformance and a client "accepting" the hardware of some vendor.
Up to 100ms is kind of ok-ish barely-sluggish, but over 100ms latency, it becomes extremely annoying to maintain a conversation.
Video conferencing often makes this worse, because it is what people use for meetings, etc. and that involves more than 2 people maintaining a conversation, so latency becomes even more important there.
Otherwise 3-4 people start talking over each other, and none of them notices until they receive what the others are saying. Which is extremely annoying.
Gaming and video conferencing come to mind. Videoconferences need bandwidth for obvious reasons but it's also nice if you don't have any delays in when you says something and when the other side hears it. I've been in some calls lately with very noticable delays. Especially people joining from mobile phones tend to be affected (shit latency, variable bandwidth).
I think Adobe been one of the worst companies I've dealt with personally, as many of the endpoints have ridiculously low timeouts (for someone with really shitty latency).