Maybe it's the timing of when I've cruised, but I've always had some type of mailed documents. From what I've read some in other countries haven't.
FWIW, my January cruise on Marina had the Themed cover, while our April cruise on Regatta had the Blue envelope and the inserts described in the Press release.
BUT, those of us that have cruised Oceania for the past 15 years or more know that the mailer has always been a part of what they send to you, along with the Final documents by email, which really have the important information in them.
Perhaps there was a short time when they didn't send anything out, but obviously I didn't cruise in that time period. Just as a data point my last Oceania cruise pre covid was in Dec of 2019 and my next one after the restart was Sept of 2022, then again March 23 and Jun of 23. I got a pre cruise booklet on all of those.
My point is I'm not sure exactly what this is all about. The only thing I can figure is the return of the Blue envelope and the NEW style luggage tags, which I posted about with pictures in March of this year.