Well, since Android 10 we are available to see the track duration in the notifications. Even some apps says that. But the problem is that on my Redmi I couldn't see that function working.
Maybe is MIUI cause such things?
Somebody has problems with this thing?
I give access to the apps for notifications but still it doesn't work.

I'm not using any other launchers and other UI or anything.
I found nothing in the web and 4pda about this thing

what music app?

sometimes it is good to delete and reinstall android, sometimes an OTA update is not 100% functional, but in new brands, of course in quotes.
if you want to flash your device here you can download the firmware and fastboot commands.
https://www.youtube.com/watch?v=cn5F12ixLB8

Marcell: VMP.
Also it doesn't work in any other music apps.
cs2d_is_a_Gem: the phone is bought like a month ago, if I do something wrong and if my phone became a brick I will lose the guarantee.

I recommend that you use the warranty and ask for a change of smartphone, you can even change the model if you wish or add more money, if your provider's policies allow it.
it is just a thought

Don't do anything Mora recommended yet, it's silly to do that before you do other debugging solutions. Reflashing would be the last step.

Can you send a Play Store link to the app? I found a VMP but found no ways to do any settings for notifications, and I have Android 10 as well. Maybe I am using a different app?

@ Marcell: you have to be registered in VKontakte to login into VMP.
https://vmp.su/
The screenshot I sent is actual settings of this app. Is not exists in the play store.

@ Mora:

You have been pwnned!

I have VKontakte

So, seems it works fine on my end, I think it's MIUI then.

Well, it might be MIUI yeah. Seems that I have to wait for MIUI 12 for some changes. Ain't like I very need in that function, but I need to figure out why it doesn't work in this phone.

Not interested in changing model or pay additional cash for another phone.