Dear Friend, I would highly recommend you to do a checkup of the phone at Samsung Authorised Service Centre. Also a little advice to take a proper backup & try to do a hard reset on the phone & use it for sometime. Once it happened with me long back ...
Samsung haven't include S8,S8+ & Note 8 for OneUI 2.0 Android 10 (Q) update. Check Notice Section, they have already mentioned the models which they will give Android 10(OneUI 2) update.
I haven't recieved yet, still waiting for the January Android Pie update too. I'm too using S9+, my security patch is of November 2019. Why their is a delay can anyone explain it to me.Edited : Just now I have recieved it.