I have recently upgraded to PHPUnit 9.5.20 and noticed that it is printing #StandWithUkraine for every test run. Eg.
Testing started at 10:01 am ...
Running in local mode
PHPUnit 9.5.20 #StandWithUkraine
Time: 00:01.141, Memory: 24.00 MB
OK (1 test, 4 assertions)
I guess you would have to edit actual source code of the package, and that seems not recommended.
But the banner is located in phpunit / src / TextUI / TestRunner.php on line 322 - 331
I guess removing it would do the trick, however I haven't tried it and don't recommend. The banner is also mentioned in a few other files. I've tracked down a commit made by the package author so you can see where the banner is mentioned. Commit by author