Seen on vagrant, after ensuring everything is up to date:
2023-05-18 19:05:48 wiki exception ERROR: [def0225a400c80d931ca5d66] [no req] Error: Interface 'Wikimedia\MetricsPlatform\EventSubmitter' not found {"exception_url":"[no req]","reqId":"def0225a400c80d931ca5d66","caught_by":"entrypoint"}
[Error Error] (/vagrant/mediawiki/extensions/EventLogging/includes/MetricsPlatform/EventSubmitter.php:12) Interface 'Wikimedia\MetricsPlatform\EventSubmitter' not found
#0 /vagrant/mediawiki/includes/AutoLoader.php(221): require()
#1 [internal function]: AutoLoader::autoload()
#2 /vagrant/mediawiki/extensions/EventLogging/includes/MetricsPlatform/MetricsClientFactory.php(39): spl_autoload_call()
#3 /vagrant/mediawiki/extensions/EventLogging/includes/EventLogging.php(62): MediaWiki\Extension\EventLogging\MetricsPlatform\MetricsClientFactory->newMetricsClient()
#4 /vagrant/mediawiki/extensions/EventLogging/includes/EventLogging.php(147): MediaWiki\Extension\EventLogging\EventLogging::getMetricsPlatformClient()
#5 /vagrant/mediawiki/extensions/WikiEditor/includes/Hooks.php(212): MediaWiki\Extension\EventLogging\EventLogging::submitMetricsEvent()
#6 /vagrant/mediawiki/extensions/WikiEditor/includes/Hooks.php(164): MediaWiki\Extension\WikiEditor\Hooks->doMetricsPlatformLogging()
#7 /vagrant/mediawiki/extensions/WikiEditor/includes/Hooks.php(509): MediaWiki\Extension\WikiEditor\Hooks->doEventLogging()
#8 /vagrant/mediawiki/includes/HookContainer/HookContainer.php(160): MediaWiki\Extension\WikiEditor\Hooks->onEditPage__attemptSave()
#9 /vagrant/mediawiki/includes/HookContainer/HookRunner.php(1543): MediaWiki\HookContainer\HookContainer->run()
#10 /vagrant/mediawiki/includes/editpage/EditPage.php(2103): MediaWiki\HookContainer\HookRunner->onEditPage__attemptSave()
#11 /vagrant/mediawiki/includes/editpage/EditPage.php(1863): MediaWiki\EditPage\EditPage->internalAttemptSave()
#12 /vagrant/mediawiki/includes/api/ApiEditPage.php(520): MediaWiki\EditPage\EditPage->attemptSave()
#13 /vagrant/mediawiki/includes/api/ApiMain.php(1914): ApiEditPage->execute()
#14 /vagrant/mediawiki/includes/api/ApiMain.php(859): ApiMain->executeAction()
#15 /vagrant/mediawiki/extensions/VisualEditor/includes/ApiVisualEditorEdit.php(131): ApiMain->execute()
#16 /vagrant/mediawiki/extensions/VisualEditor/includes/ApiVisualEditorEdit.php(449): MediaWiki\Extension\VisualEditor\ApiVisualEditorEdit->saveWikitext()
#17 /vagrant/mediawiki/includes/api/ApiMain.php(1914): MediaWiki\Extension\VisualEditor\ApiVisualEditorEdit->execute()
#18 /vagrant/mediawiki/includes/api/ApiMain.php(890): ApiMain->executeAction()
#19 /vagrant/mediawiki/includes/api/ApiMain.php(861): ApiMain->executeActionWithErrorHandling()
#20 /vagrant/mediawiki/api.php(93): ApiMain->execute()
#21 /vagrant/mediawiki/api.php(48): wfApiMain()
#22 /var/www/w/api.php(5): require(string)
#23 {main}No idea what's going on here, Wikimedia\MetricsPlatform\EventSubmitter is in the Composer autoload classmap but somehow still doesn't get autoloaded.