ObjectEditorIT.preventUsersToLeaveTheEditorWithoutSaving is flickering

TimedPromise timed out after 300000 ms
Build info: version: '3.141.59', revision: 'e82be7d358', time: '2018-11-14T08:17:03'
System info: host: '58902d3dc02b', ip: '172.17.0.2', os.name: 'Linux', os.arch: 'amd64', os.version: '4.19.0-16-cloud-amd64', java.version: '11.0.6'
Driver info: org.openqa.selenium.remote.RemoteWebDriver
Capabilities {acceptInsecureCerts: true, browserName: firefox, browserVersion: 89.0, javascriptEnabled: true, moz:accessibilityChecks: false, moz:buildID: 20210527174632, moz:geckodriverVersion: 0.29.0, moz:headless: false, moz:processID: 300, moz:profile: /tmp/rust_mozprofilewdjBsL, moz:shutdownTimeout: 60000, moz:useNonSpecCompliantPointerOrigin: false, moz:webdriverClick: true, pageLoadStrategy: normal, platform: LINUX, platformName: LINUX, platformVersion: 4.19.0-16-cloud-amd64, setWindowRect: true, strictFileInteractability: false, timeouts: {implicit: 0, pageLoad: 300000, script: 30000}, unhandledPromptBehavior: ignore, webdriver.remote.sessionid: 02151087-4c92-4c88-8e85-5f9...}
Session ID: 02151087-4c92-4c88-8e85-5f9ae9be7c2f

org.openqa.selenium.TimeoutException: 
TimedPromise timed out after 300000 ms
Build info: version: '3.141.59', revision: 'e82be7d358', time: '2018-11-14T08:17:03'
System info: host: '58902d3dc02b', ip: '172.17.0.2', os.name: 'Linux', os.arch: 'amd64', os.version: '4.19.0-16-cloud-amd64', java.version: '11.0.6'
Driver info: org.openqa.selenium.remote.RemoteWebDriver
Capabilities {acceptInsecureCerts: true, browserName: firefox, browserVersion: 89.0, javascriptEnabled: true, moz:accessibilityChecks: false, moz:buildID: 20210527174632, moz:geckodriverVersion: 0.29.0, moz:headless: false, moz:processID: 300, moz:profile: /tmp/rust_mozprofilewdjBsL, moz:shutdownTimeout: 60000, moz:useNonSpecCompliantPointerOrigin: false, moz:webdriverClick: true, pageLoadStrategy: normal, platform: LINUX, platformName: LINUX, platformVersion: 4.19.0-16-cloud-amd64, setWindowRect: true, strictFileInteractability: false, timeouts: {implicit: 0, pageLoad: 300000, script: 30000}, unhandledPromptBehavior: ignore, webdriver.remote.sessionid: 02151087-4c92-4c88-8e85-5f9...}
Session ID: 02151087-4c92-4c88-8e85-5f9ae9be7c2f
	at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
	at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
	at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
	at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:490)
	at org.openqa.selenium.remote.http.W3CHttpResponseCodec.createException(W3CHttpResponseCodec.java:187)
	at org.openqa.selenium.remote.http.W3CHttpResponseCodec.decode(W3CHttpResponseCodec.java:122)
	at org.openqa.selenium.remote.http.W3CHttpResponseCodec.decode(W3CHttpResponseCodec.java:49)
	at org.openqa.selenium.remote.HttpCommandExecutor.execute(HttpCommandExecutor.java:158)
	at org.openqa.selenium.remote.RemoteWebDriver.execute(RemoteWebDriver.java:552)
	at org.openqa.selenium.remote.RemoteWebDriver.get(RemoteWebDriver.java:277)
	at org.xwiki.test.ui.XWikiWebDriver.get(XWikiWebDriver.java:627)
	at org.xwiki.test.ui.TestUtils.gotoPage(TestUtils.java:710)
	at org.xwiki.test.ui.TestUtils.gotoPage(TestUtils.java:699)
	at org.xwiki.test.ui.TestUtils.gotoPage(TestUtils.java:691)
	at org.xwiki.test.ui.TestUtils.gotoPage(TestUtils.java:633)
	at org.xwiki.test.ui.TestUtils.gotoPage(TestUtils.java:619)
	at org.xwiki.flamingo.test.docker.ObjectEditorIT.preventUsersToLeaveTheEditorWithoutSaving(ObjectEditorIT.java:88)