vim.validate is deprecated
I don't think this will cause problems anytime soon, as it'll be removed in 1.0, but I think it's worth tracking. The advice seems a tad weird, because it suggests to use vim.validate(name, value, validator, optional_or_msg) instead.
Thanks for the heads-up! I will look into this soon. I haven't seen any deprecation messages yet, but I probably need to update my nvim installation.
I saw this too, they're changing the api for validate. I believe the reason is because it's a widely-used lib function (used in all kinds of contexts that they don't have control over), and creating a new table for each call (via the former api) can become a performance bottleneck in a hot/tight loop.