Right-click the user's name or avatar while in the VC or in the server member list.
Since voice chat data is not archived by Discord, the following information strengthens your report: How To Report Someone on Discord | Desktop and Mobile
To report someone for instigating or abusive behavior in a Discord Voice Channel (VC), you should primarily utilize the in-app reporting tools or the official Discord Support Request Form. Because Discord does not record or store the audio from voice chats, providing external evidence like screenshots or recordings of related text behavior is often necessary. In-App User Report :