I actually just disable that with '(lsp-ui-doc-enable nil) in spacemacs custom-set-variables. But it would probably be better to raise an error on lsp-ui. It looks like there is a semi-related issue open already: Too small window for docstring · Issue #267 · emacs-lsp/lsp-ui · GitHub And perhaps you could try setting lsp-ui-doc-use-webkit to t?
