This is what I would do if this was my phone @Mjf69
Please make sure all your apps are updated both in your Playstore and Samsung Galaxy Store.
Put the phone in Safe Mode which disables your downloaded app's but let's your stock app's keep working. If the issues stop then this highlights a downloaded app as the possible issue. Come out of Safe Mode and start deleting your most recent downloaded app's one at a time until it stops. https://www.samsung.com/uk/support/mobile-devices/how-to-start-my-galaxy-device-in-safe-mode/
Clear your phone's System Cache Files by turning your phone Off and then from a set series of button presses go into the phone's System Files and clear the cache. No information is lost this way. You may need to insert your headphones or hook upto a computer with your data cable to get to this menu on the phone. https://www.samsung.com/uk/support/mobile-devices/how-do-i-clear-the-cache-on-my-device/
Back up then remove any relevant sd card and factory reset.
Not going to do a factory reset...this isn't a solution in my eyes. Too many passwords .. banking etc to try and remember. There needs to be a way to clear out all information when you delete the app...it leaves stuff behind
