I wonder if it may be a TCL or remote issue. (or perhaps just something flaky with your particular TV).
I haven't experienced either of these behaviors on my Insignia RokuTV.
Does this happen to you in both the Antenna/OTA Guide and the Roku Channel TV Guide?
Also seems strange that the overlay banner on bottom of screen would reappear again after tuning into Channel. (normally pressing the OK button toggles the overlay banner on/off). That is why I am thinking it may just be a bad remote, and not the TV or the Guide (at least at first glance.) It is of course, entirely possible there is a bug in the OS, but haven't seen additional reports of this yet in the Community.
Try downloading the official Roku Mobile Remote App to a mobile device (phone or tablet) available in the Play/Apple stores. Then take the batteries out of your physical remote to disable it and avoid it from interfering with anything. Then try using the Remote app and see if this resolves your issue.
I understand it only happens intermittently, but I think this may be a necessary step in diagnosing the problem with the channel browsing/scrolling.
Feel free to post back with an update or if you need more help.
Edited: I stand corrected. @Benedlr reported seeing the overlay banner issue on his TCL RokuTV as recently as yesterday. (https://community.roku.com/t5/Discussions/Channel-guide-is-now-timed/m-p/761525#M24100) This may turn out to be a bug affecting TCL RokuTVs. (or at least an undesired feature.)
Roku Community Streaming Expert
Just another Roku user... I am not a Roku employee.
Insignia RokuTV, Ultra 4660x, Premiere+ 3921, Express 4k+ 3941