To figure out what is changed on a layer press the U key twice and look for everything that pops up in the timeline. This will not only tell you what effects are used on that layer, it will tell you exactly what settings and controls were modified from their original values.
You can also expand the flow chart and see every plug-in listed that is used on every layer in the project.
Collect files never gave you a list of effects, it just gives you a project file with the comps and nested comps(pre-comps), and the assets (footage and stills) that are used in the project.
Op is correct. Collect files gives a report by default that also lists all the effects used. This was removed due to a bug in CC2017, but fixed in the latest update. You should update your software and they will show in the report.
I stand corrected. I use collect files all the time but I guess I never read the report before because I've never had a problem the report could solve. I did check the report but on a machine that had not yet been updated yet because I never update in the middle of a project....
I too rarely use it or need it but it's a good way to get useful information about the the project especially for archive purposes. you can create the just report even without collecting and this too is useful to get a peak on what's going on in the project. you get a lists of effects (or plugins) used in all of the project, fonts (very nice) and see the media that was used and its size and current location before it was collected, and the lists of compositions. it's also a good way to see if your students were organized through the project too, and didn't save their files all over the place (desktop!)