user-1: 
Locks are stored in memory only. Nodes start with zero locked outputs, and the locked output list
is always cleared (by virtue of process exit) when a node stops or fails.

https://bitcoincore.org/en/doc/0.21.0/rpc/wallet/lockunspent/

user-1: Because it was added as memory-only filter by Jeff Garzik in PR: https://github.com/bitcoin/bitcoin/pull/1861/

It might be nice to store this in the wallet, but to judge interest and review the interface, this is a useful first step.

Couple of users who care about privacy wanted persistency for locking unspents and created issue: https://github.com/bitcoin/bitcoin/issues/14907 but it was closed in May 2020 because of lack of interest.
A pull request has been merged today (26 Sep 2021) to fix this issue by Meshcollider: https://github.com/bitcoin/bitcoin/pull/23065. It adds a parameter which can be set to true for saving lock state in database. It's persistent by default in GUI coin control options.

-1: <blockquote>
<p><strong>Locks are stored in memory only</strong>. Nodes start with zero locked outputs, and the locked output list
is always cleared (by virtue of process exit) when a node stops or fails.</p>
</blockquote>
<p><a href="https://bitcoincore.org/en/doc/0.21.0/rpc/wallet/lockunspent/" rel="nofollow noreferrer">https://bitcoincore.org/en/doc/0.21.0/rpc/wallet/lockunspent/</a></p>
 -1: <p>Because it was added as memory-only filter by Jeff Garzik in PR: <a href="https://github.com/bitcoin/bitcoin/pull/1861/" rel="nofollow noreferrer">https://github.com/bitcoin/bitcoin/pull/1861/</a></p>
<blockquote>
<p>It might be nice to store this in the wallet, but to judge interest and review the interface, this is a useful first step.</p>
</blockquote>
<p>Couple of users who care about privacy wanted persistency for locking unspents and created issue: <a href="https://github.com/bitcoin/bitcoin/issues/14907" rel="nofollow noreferrer">https://github.com/bitcoin/bitcoin/issues/14907</a> but it was closed in May 2020 because of lack of interest.</p>
<p>A pull request has been merged today (26 Sep 2021) to fix this issue by Meshcollider: <a href="https://github.com/bitcoin/bitcoin/pull/23065" rel="nofollow noreferrer">https://github.com/bitcoin/bitcoin/pull/23065</a>. It adds a parameter which can be set to true for saving lock state in database. It's persistent by default in GUI coin control options.</p>
