I think a lot of people, including myself, still stuck at BS 5.x due to the breaking changes introduced in BS 7.x
There’s an upgrade guide: https://bucklescript.github.io/docs/en/upgrade-to-v7
It turned out to be easier than I thought thanks to the community effort.
I had some minor problems with some old packages like https://github.com/astrocoders/recontainers, https://github.com/Astrocoders/bs-react-native-jsx3-compat/ and https://github.com/astrocoders/bs-react-native-paper but I could patch them just fine
Cool stuff that I found after upgrading:
Errorin scope by default