Apple Watch on watchOS 26 can’t be paired after iPhone downgrade to iOS 18.5

After joining the developer beta on both my iPhone and Apple Watch, I downgraded my iPhone back to iOS 18.5 using a factory reset and a backup. I did the same for my Apple Watch, but now it won’t pair — it says I need a device running iOS 26 to set it up, since that’s the version it was previously using.

It also tells me to contact Apple Support for assistance, but since I’m in Kazakhstan, there’s no official Apple service here, so I’m not sure what to do next.