MentionsIT#comment is flickering

org.openqa.selenium.TimeoutException: 
Failed after [10] attempts. Expected: [1] - Latest value received: [2].
Build info: version: '4.21.0', revision: '79ed462ef4'
System info: os.name: 'Linux', os.arch: 'amd64', os.version: '4.19.0-16-cloud-amd64', java.version: '17.0.11'
Driver info: driver.version: unknown
	at org.xwiki.platform.notifications.test.po.NotificationsTrayPage.waitOnNotificationCount(NotificationsTrayPage.java:118)
	at org.xwiki.mentions.test.ui.MentionsIT.lambda$comment$6(MentionsIT.java:182)
	at org.xwiki.mentions.test.ui.MentionsIT.runAsUser(MentionsIT.java:217)
	at org.xwiki.mentions.test.ui.MentionsIT.comment(MentionsIT.java:180)