DVD M-Disc appears to have been discontinued by CMC (who bought Verbatim from Mitsubishi in 2019, and also Taiyo Yuden in 2015).
Millenniata claimed that their M-DISC DVD recordings would last 1000 years if properly stored, but the company went bust in 2016 (the original discs were made by Ritek), after the French National Laboratory of Metrology and Testing found that the discs may have still been readable after 250 hours of accelerated aging, however with an error rate above threshold (yep, sounds like Ritek)
I have only ever bought "Azo" branded Verbatim which have seemed fine whether made by MCC in Singapore, Falcon Technologies (FTI) in UAE, or even (gasp!) Moser-Baer in India. I avoided Verbatim "DataLife" (not "DataLifePlus"), "Life Series" and "Value Series" which have always been made by CMC Taiwan, Ritek or Moser-Baer. Don't know who made their M-Disc but it may well have been Ritek as they were already equipped to make them.
In any case I don't think you can count on them lasting 1000 years. After all we've already discovered some microorganisms that can eat polycarbonate