Going forward, the best (only) option is to use the upstream homebrew jemalloc formula, but before doing so we need to figure out what changes are needed in it to avoid https://github.com/neovim/neovim/issues/5681. That means sending a pull request to homebrew core.
Linking static library libjemalloc.a solves the problem, just as a workaround.
(Haven't found out formula-suitable way to choose appropriate library yet)
In this commit we disabled jemalloc because it of https://github.com/neovim/neovim/issues/5681, which was caused by an attempt to fix https://github.com/neovim/homebrew-neovim/issues/194.
Going forward, the best (only) option is to use the upstream homebrew jemalloc formula, but before doing so we need to figure out what changes are needed in it to avoid https://github.com/neovim/neovim/issues/5681. That means sending a pull request to homebrew core.
Then we can restore
depends_on "jemalloc" => :recommended
(i.e. revert https://github.com/neovim/homebrew-neovim/pull/200).