First try putting the phone in Safe Mode which disables any downloaded apps and leaves the stock ones working and then see what happens.
Check there are no software updates in your phones settings.
If it continues then if this was my situation I'd back up and factory reset.
If it continues still then seek support from a Samsung Experience Store / Samsung Service Centre
My advice comes from being a UK Samsung Phone Owner.
I have no affiliation with Samsung.
Current Phone ~
Samsung Note 10 Plus 5G _256Gb >_ Samsung One Ui 2.5/ Android 10.
I also have the same problem: it started 12th of July 2020.
I might have an hardware issue, as it does not turn on unless I connect a charger to it for 1 minute, then disconnect the charger, waith another minute and then the phone starts.