I’m not sure if I can be of much help, but the first 2 things I would try are 1. Semi-hard reset the TV; you can do this by either unplugging the TV then replugging it in about 30 seconds later or easier yet; start the TV and after it fully boots hold down the physical remotes power button until the TV restarts (you see the screen produce an image which will usually will be OLED/QLED/Samsung or something similar). What this does is basically act just like you restarting your comouter or phone when it acts up clearing the bad acting program just in limbo. If this doesn’t work you can number 2 always go to your TV’s settings menu and then go down to support. You should see an option called device care click this and run it. This clears the cache of all the apps on the TV and could possible fix the issue if their is a corrupt file or file causing it to lag speeding it up.
If these don’t help, I would like to ask what version of the app were you using before? I ask as awhile ago they changed the app’s remote function to look just like the TV’s remote sometime the middle of last year. Before this it only had a touchpad mode. The new version has a seperate button that always you to change between a standard click remote and slide touchpad mode (see attached photos below of new app remote; old remote looks like the one from this post: Q70R Smart TV - #8 by DaWeav).
If nothing I said helps fix it I would then suggest you contact Samsung through their Members App or on the phone to try to escalate the issue with support.
