Completion preview/popup extra information filetype highlight?

[dunrix]

When LSCClientShowHover or LSCClientSignatureHelp are invoked, a preview window gets correct filetype set and corresponding syntax highlighting - result after ShowHover on collect method:

When invoking symbol completion and Vim's completeopt includes preview or popup option, extra information is not syntax-highlighted, filetype is unset - lsc#complete#complete invoked on .col token:

Is there a way how to set syntax highlighting for completion extra info window also? Like filetype=markdown or dynamically by current filetype of buffer in which is it invoked?