Same, happened to me twice, but i had elytra 😉
I've had the same thing on my realm, although it looks to me like that would be an intended feature. Entities seem to be able to move minecarts on any type of rail. This also happened to me with zombie villagers and villagers in minecarts, them going uphill / moving on unpowered rails. At the end of your track, take off the last rail: that'll stop the villager from moving on the track. Also remember that rails can be pulled/pushed with pistons on the same height level between two blocks, and detector rails can be used to trigger these pistons. Hope it helps you a bit, cheers
Antoine
Seems to still be happening after the “Chase the Skies” update on June 17th. The ore looks blue-ish from up close. Attached are my current options.txt file with the VV settings.
Version: v1.21.90
Build: 34110009
Branch: r/21_u9
SHA: a1f847ef645b02c6b95212b218488342