My s9+ did a software update last week overnight whilst I slept, since besides the change in the look of the operating system my battery is losing power almost double as quickly as it was previously. For all my calendar appointments I have duplicates but with 'content hidden' on them and opening my apps is slower and the screen is more flickers rather than smooth when changing. Has anyone else had this and what can I do to get Samsung to sort it back out? Thanks.
Try putting the phone in Safe Mode which disables any downloaded apps and leaves the stock ones working and then see what happens. If things return to normal then one or more of your apps are not optimised. Come out of Safe Mode and start deleting your most recent apps one at a time until it stops.
If a phone glitches still after a few days from the update and still in Safe Mode then I'd suggest to turn the phone Off and then from a set series of button presses go into the phones system files and clear the cache. No info is lost this way.
If that does not help then back up and remove any relevant Sd card and factory reset as a last resort.