A self-hosted URL shortener: Shlink - Keep control over all your shortened URLs, by serving them under your own domains, using this simple yet powerful tool. https://shlink.io/
I was very surprised to find this mature, full-featured URL shortener. It’s written in PHP and includes Geoblocking so your shortener isn’t abused.
A Docker quick-start guide: https://lnk.clifmo.com/ljk13
I find link shorteners useful for sharing (ephemeral) links to others (especially if they’re massive) but for linking stuff on the web where you can hide it under an anchor tag is definitely a bad idea.