For new users' information: REAPER prereleases are open for anyone to try out and test.
The prerelease cycle varies, but generally the first prerelease for the next version is posted a few days after an official version release. There will then be a number of prerelease updates over the following few days or weeks, until the prerelease becomes the new release version.
Where to download, and other general information about prereleases
here.
The discussion and bug reports thread for the current prerelease version is always stickied at the top of the
prerelease forum.
If you do try out the prerelease version and have some comments, please post in one of those threads, not here! Thanks.