Since https://gerrit.wikimedia.org/r/c/mediawiki/core/+/719503 I'm seeing:
from /srv/mediawiki/w/includes/parser/PPFrame_Hash.php(88) #0 /srv/mediawiki/w/includes/parser/Preprocessor_Hash.php(71): PPFrame_Hash->__construct(Preprocessor_Hash) #1 /srv/mediawiki/w/extensions/PortableInfobox/includes/services/Helpers/PortableInfoboxParsingHelper.php(33): Preprocessor_Hash->newFrame() #2 /srv/mediawiki/w/extensions/PortableInfobox/includes/services/PortableInfoboxDataService.php(199): PortableInfobox\Helpers\PortableInfoboxParsingHelper->parseIncludeonlyInfoboxes(Title) #3 /srv/mediawiki/w/extensions/PortableInfobox/includes/PortableInfobox.hooks.php(45): PortableInfoboxDataService->reparseArticle(boolean) #4 /srv/mediawiki/w/includes/HookContainer/HookContainer.php(338): PortableInfoboxHooks::onPageContentSave(WikiPage, User, WikitextContent, CommentStoreComment, integer, NULL, NULL, integer, Status) #5 /srv/mediawiki/w/includes/HookContainer/HookContainer.php(137): MediaWiki\HookContainer\HookContainer->callLegacyHook(string, array, array, array) #6 /srv/mediawiki/w/includes/HookContainer/HookRunner.php(2811): MediaWiki\HookContainer\HookContainer->run(string, array) #7 /srv/mediawiki/w/includes/Storage/PageUpdater.php(789): MediaWiki\HookContainer\HookRunner->onPageContentSave(WikiPage, User, WikitextContent, CommentStoreComment, integer, NULL, NULL, integer, Status) #8 /srv/mediawiki/w/includes/page/WikiPage.php(2225): MediaWiki\Storage\PageUpdater->saveRevision(CommentStoreComment, integer) #9 /srv/mediawiki/w/includes/page/WikiPage.php(2080): WikiPage->doUserEditContent(WikitextContent, User, CommentStoreComment, integer, boolean, array, integer) #10 /srv/mediawiki/w/includes/EditPage.php(2361): WikiPage->doEditContent(WikitextContent, string, integer, boolean, User, string, array, integer) #11 /srv/mediawiki/w/includes/EditPage.php(1694): EditPage->internalAttemptSave(array, boolean) #12 /srv/mediawiki/w/includes/EditPage.php(669): EditPage->attemptSave(array) #13 /srv/mediawiki/w/includes/actions/EditAction.php(71): EditPage->edit() #14 /srv/mediawiki/w/includes/actions/SubmitAction.php(38): EditAction->show() #15 /srv/mediawiki/w/includes/MediaWiki.php(531): SubmitAction->show() #16 /srv/mediawiki/w/includes/MediaWiki.php(315): MediaWiki->performAction(Article, Title) #17 /srv/mediawiki/w/includes/MediaWiki.php(913): MediaWiki->performRequest() #18 /srv/mediawiki/w/includes/MediaWiki.php(546): MediaWiki->main() #19 /srv/mediawiki/w/index.php(53): MediaWiki->run() #20 /srv/mediawiki/w/index.php(46): wfIndexMain() #21 {main}
Though it includes the PortableInfobox extension in the trace, so maybe it's the extension fault?
https://github.com/lkucharczyk/mediawiki-PortableInfobox/blob/master/includes/services/Helpers/PortableInfoboxParsingHelper.php#L33 is the line it points to.