The bibliography uses the normal paragraph spacing value, which you can set for the whole document via
#set par(spacing: ...) // Default: 1.2em
Usually, the default value looks fine, but your increased line spacing makes it look disproportionate. If you want different spacing just for the bibliography, you can limit the above set rule or decrease the line spacing with a show-set rule
#show bibliography: set par(spacing: ..., leading: ...)
The default leading value (used for line spacing) is 0.65em.
thanks for your answer!
Even though the actual documentation of Typst Paragraphs contains the variable spacing, somehow I always get the error unknown variable: spacing. If you are familiar with this issue, please reach out to me.
It appears you are using an outdated Typst version; you’ll need to use Typst 0.12.0 for #set par(spacing: ...) to work. (It used to be set block(spacing: ...) in previous versions, which still works but is no longer useful for paragraphs themselves.)