I see that there are various cases of this specific error "Using ${var} in strings is deprecated, use {$var} instead" in PHP 8.2.
Example:
$ arc unit --everything Done. PASS 302ms PhabricatorLibraryTestCase::testLibraryMap FAIL PhabricatorLibraryTestCase::testEverythingImplemented EXCEPTION (Exception): Error while loading file "/var/www/phorge/src/applications/herald/phid/HeraldTranscriptPHIDType.php": Using ${var} in strings is deprecated, use {$var} instead #0 /var/www/arcanist/src/init/lib/PhutilBootloader.php(211): PhutilBootloader->executeInclude('...') #1 /var/www/arcanist/src/symbols/PhutilSymbolLoader.php(423): PhutilBootloader->loadLibrarySource('...', '...') #2 /var/www/arcanist/src/symbols/PhutilSymbolLoader.php(277): PhutilSymbolLoader->loadSymbol(Array) #3 /var/www/arcanist/src/__tests__/PhutilLibraryTestCase.php(16): PhutilSymbolLoader->selectAndLoadSymbols() #4 /var/www/arcanist/src/unit/engine/phutil/PhutilTestCase.php(634): PhutilLibraryTestCase->testEverythingImplemented() #5 /var/www/arcanist/src/unit/engine/PhutilUnitTestEngine.php(69): PhutilTestCase->run() #6 /var/www/arcanist/src/unit/engine/ArcanistConfigurationDrivenUnitTestEngine.php(148): PhutilUnitTestEngine->run() #7 /var/www/arcanist/src/workflow/ArcanistUnitWorkflow.php(170): ArcanistConfigurationDrivenUnitTestEngine->run() #8 /var/www/arcanist/scripts/arcanist.php(427): ArcanistUnitWorkflow->run() #9 {main}