Delta was going to reissue the ticket for me and then stupid me asked about rebooking possibilities and the agent asked superiors. They said only AF can reissue the ticket (since they took control of it, although the ticket was originally issued on 006 stock) and DL covid waivers don't apply.
If anybody has a suggestion which DL office to contact to get the ticket reissued on DL stock after all, please send me a PM. Do not comment on this post.
I am worried that my ticket has been annotated anyway, but I'd like to give it a last try before asking for a refund.