RealtimeWYSIWYGEditorIT#syntaxChange is flickering

Expected condition failed: waiting for org.xwiki.test.ui.XWikiWebDriver$$Lambda$1705/0x00007f025cc43668@7c522eca (tried for 10 second(s) with 500 milliseconds interval)
Build info: version: '4.39.0', revision: '126f156aee'
System info: os.name: 'Linux', os.arch: 'amd64', os.version: '6.1.0-37-cloud-amd64', java.version: '17.0.17'
Driver info: org.xwiki.test.ui.XWikiWebDriver
Capabilities {acceptInsecureCerts: true, browserName: firefox, browserVersion: 146.0.1, container:hostname: 38069012d447, moz:accessibilityChecks: false, moz:buildID: 20251217121356, moz:firefoxOptions: {prefs: {dom.disable_beforeunload: false, remote.active-protocols: 1, remote.events.async.enabled: false}}, moz:geckodriverVersion: 0.36.0, moz:headless: false, moz:platformVersion: 6.1.0-37-cloud-amd64, moz:processID: 183, moz:profile: /tmp/rust_mozprofileJNq74t, moz:shutdownTimeout: 60000, moz:webdriverClick: true, moz:windowless: false, pageLoadStrategy: normal, platformName: linux, proxy: Proxy(), se:cdpEnabled: false, se:containerName: 38069012d447, se:deleteSessionOnUi: true, se:downloadsEnabled: true, se:gridWebSocketUrl: ws://127.0.0.1:35559/sessio..., se:noVncPort: 7900, se:vnc: ws://172.17.0.5:4444/sessio..., se:vncEnabled: true, se:vncLocalAddress: ws://172.17.0.5:7900, setWindowRect: true, strictFileInteractability: false, timeouts: {implicit: 0, pageLoad: 300000, script: 30000}, unhandledPromptBehavior: ignore, userAgent: Mozilla/5.0 (X11; Linux x86..., webSocketUrl: ws://172.17.0.5:4444/sessio...}
Session ID: 39bed066-367b-448d-bd3b-a232b0bd86b9
	at org.openqa.selenium.support.ui.WebDriverWait.timeoutException(WebDriverWait.java:84)
	at org.openqa.selenium.support.ui.FluentWait.until(FluentWait.java:228)
	at org.xwiki.test.ui.XWikiWebDriver.waitUntilCondition(XWikiWebDriver.java:228)
	at org.xwiki.test.ui.XWikiWebDriver.waitUntilElementsAreVisible(XWikiWebDriver.java:330)
	at org.xwiki.test.ui.XWikiWebDriver.waitUntilElementIsVisible(XWikiWebDriver.java:285)
	at org.xwiki.test.ui.XWikiWebDriver.waitUntilElementIsVisible(XWikiWebDriver.java:273)
	at org.xwiki.test.ui.po.BaseElement.waitForNotificationMessage(BaseElement.java:110)
	at org.xwiki.test.ui.po.BaseElement.waitForNotificationSuccessMessage(BaseElement.java:88)
	at org.xwiki.realtime.wysiwyg.test.ui.RealtimeWYSIWYGEditorIT.syntaxChange(RealtimeWYSIWYGEditorIT.java:2298)