Firefox Nightly isn't really designed to be a regular browser that you use for your regular browsing. It's there mainly for testing purposes, so that people can find bugs.

Because it gets updated so often (twice daily) and the features are constantly being changed, removed or added, there really aren't any official release notes published for Firefox Nightly. Release notes would be hard to keep updated. Release notes aren't really consistent until a version reaches Firefox Beta, because the features in Beta are more stable, require fewer changes and are (more or less) how they will appear in the release.

The closest thing you have to release notes for Firefox Nightly is the push log on Mozilla Central. It shows every change that's pushed into the Firefox Nightly version. There are a lot of changes and the notes for each change are technical, but there are indeed a lot of changes made to Firefox Nightly on a daily basis.

For example, yesterday (Sunday, April 19, 2020) there were just short of 40 changes. Today, I see more than 40 changes already made. Because of the sheer volume of changes, that's why Firefox Nightly updates are released twice a day.

If you are unhappy with the frequent changes in Firefox Nightly, but still want to test the newest Firefox features, perhaps Firefox Beta is a better version for you.

Firefox Nightly isn't really designed to be a regular browser that you use for your regular browsing. It's there mainly for testing purposes, so that people can find bugs. Because it gets updated so often (twice daily) and the features are constantly being changed, removed or added, there really aren't any official release notes published for Firefox Nightly. Release notes would be hard to keep updated. Release notes aren't really consistent until a version reaches Firefox Beta, because the features in Beta are more stable, require fewer changes and are (more or less) how they will appear in the release. The closest thing you have to release notes for Firefox Nightly is the push log on Mozilla Central. It shows every change that's pushed into the Firefox Nightly version. There are a lot of changes and the notes for each change are technical, but there are indeed a lot of changes made to Firefox Nightly on a daily basis. For example, yesterday (Sunday, April 19, 2020) there were just short of 40 changes. Today, I see more than 40 changes already made. Because of the sheer volume of changes, that's why Firefox Nightly updates are released twice a day. If you are unhappy with the frequent changes in Firefox Nightly, but still want to test the newest Firefox features, perhaps Firefox Beta is a better version for you.

Thanks for the detailed and logical explanation