FLR(M)-Exceptionally complex issues email

Hello
I have applied for my FLR(M)-spouse visa extension on 1st April 2020. As we all know that due to current situation all visa centres are closed so biometrics is not possible but in the mean time I have uploaded my docs on the UKVCAS portal.
But on Friday I received an email from UKVI stating that my application has raised exceptionally complex issues and will take longer to process than normal standard time.
Can somebody please advise me what this is about, because as per my knowledge until we don't submit our biometrics HO don't process applications. But by the looks of their email it shows they are processing my case if I am not wrong?
Looking forward to your response.
Best

It is a generic auto email. Many get it.

Thanks @CR001 for your response.
Yes I have noticed from this board that many people did get this email. Only thing that concerns me was the timing as I didn't give my biometrics so just raised questions in my head so though better to share and find out any possible answers.

They are processing cases, strangely enough.

I sent 3 FLR(FP) application and 2 naturalisation applications since lock down, and all of them were asked to send documents through email to casework team, without biometrics enrollment having been undertaken.

Therefore there are some degree of processing going on, although it troubles me why this is happening without biometrics enrollment.

I was even asking myself the other day, whether this is infact lawful at all. Then again Home Office has been doing lots of things which are unlawful anyway.

I think UKVI now have realized even lately that the number of online applications have been incredibly piling up and to diminish this load they have adopted such informal demeanour. But in my opinion still the final decision might not be made until the biometrics enrolment won't be completed and cleared.