@mixos ugh, sorry, I should have explained better. To test a patch you’ll need to have a development environment for WordPress. That’s usually a “local” install on your computer and needs a lot of extra dev. tools like svn, git, npm, grunt, etc.
Alternatively if you have a “staging” feature or a test install on your web host you can use the WP Tester plugin to test the latest code. Currently this is WP 5.7-alpha. Just keep in mind that’s not recommended for a live site. Going to commit the above patch so it will be possible to test that way too.