Environment - PHP extension sodium
The php-sodium extension provides strong encryption capabilities in an easy and consistent way. This extension is required from Moodle 4.2.
Note that it is still highly recommended to use php-sodium in Moodle 3.11, 4.0 and 4.1, which also support the extension. Sites which do not have this extension installed use a php-openssl based solution as a fallback, which is considered sub-optimal. See MDL-71421 for more details.
It might be useful to copy the \server\php\libsodium.dll library to \server\apache\bin\libsodium.dll - as mentioned in https://moodle.org/mod/forum/discuss.php?d=444514
See also https://www.php.net/manual/book.sodium.php and https://py-ipv8.readthedocs.io/en/latest/preliminaries/install_libsodium/