Andrew Nacin

In WordPress 3.5, the Link Manager (which some use to build blogrolls) will 
be disabled by default. If you have links when you update, it’ll still be there. 
But you can use this plugin to ensure it will always be there, even if you 
update to a later version of WordPress or remove all of your current links.

Link Manager

Works on WP 6.1

Enables the Link Manager that existed in WordPress until version 3.5.

thaomarky

Shortlink Manager TMP helps you create and manage short links easily. You can create, edit and delete short links and track clicks.
Main functions: 
– Create, edit, delete shorten links quickly and conveniently 
– Can customize slug with any keyword 
– Search by slug or link 
– Warning when deleting links 
– Sort by ID or click order 
– Paginate 10 links in page 
– QR code generation for shortlink

Shortlink Manager TMP

Short Description: Converts website links into short URLs. Easy to configure, with tracking features.

Link Manager vs Shortlink Manager TMP