Backlink value doesn't necessarily disappear the moment a domain expires, but how much of it remains usable depends heavily on what happens next.
Existing Links Often Continue Pointing to the Domain Regardless
External sites linking to the old domain typically don't remove those links just because the domain has expired, at least not right away.
Whether That Value Transfers Depends on What You Build
Genuine, relevant content on the reacquired domain gives those existing links continued reason to be considered valuable; an empty or irrelevant site doesn't.
Some Decay in Link Value Should Be Expected Over Time
Even under the best circumstances, a meaningful gap in a domain's active use tends to result in some natural decay in how much of its original link value persists.
Next step: Use the Wayback Expired Domains to check how a domain's historical backlink-worthy content compares to what you plan to build.