I'm pretty sure you've seen this message before, and probably multiple times. I got this feedback from MOS:
"The issue is caused by the way that the browser interacts with the Eloqua servers. Tthe most important reason why I would recommend using a certified browser is because it is easier to file a development ticket for these kinds of issues. If the logs show that a non-certified browser is being used there is a high possibility of the ticket being rejected, but if the issue is happening while using a certified browser it proves that the issue is not being caused by the browser. If you do notice the errors occurring in high frequency again while using a certified browser please let us know and we will be happy to help."
MOS also gave me this link so you can check if your browser AND its version are supported: https://docs.oracle.com/cloud/latest/marketingcs_gs/OMCAA/index.html#cshid=SystemRequirements.
As long as your are on a certified browser and if you get repeated "Not our finest moment" messages, MOS encourages the submission of a Service Request..
I feel that sometimes ELQ just times out, because I'll get the message but be able to click OK or CONTINUE and keep working. I'm not going to take time to report those one-off situations. But there are times that the message just keeps coming back. I'll make time to report those.