Are you referring to this? Or to the little notification on the top right when you copy text off a website?
Have you used the "pin" option on items you don't want cleared off your clipboard? You can control which items your want deleted and which ones you want saved. I usually also keep web addresses of things that I want to research later, and also have arrows and such pinned too.
However, if I'm writing a lengthy comment (I tend to get long-winded at times 😁), I compose my draft in a "character count" app. It saves my work, since the app I'm on either refreshes or times out, and if I don't save it, I lose all I've written. So now I compose my thoughts on a separate note, then copy it over (it also helps me not exceed any character limit, since I tend to do that too in reviews, etc).
However, if I'm writing a lengthy comment (I tend to get long-winded at times 😁), I compose my draft in a "character count" app. It saves my work, since the app I'm on either refreshes or times out, and if I don't save it, I lose all I've written. So now I compose my thoughts on a separate note, then copy it over (it also helps me not exceed any character limit, since I tend to do that too in reviews, etc).
I wouldn't disable notification access. I would assume your system needs that permission. I've taken some screenshots of my system settings (I've omitted the irrelevant items). You can compare them to your settings. I won't bother explaining how to get to each setting, since you seem capable. Also, are you using the samsung keyboard? And are you using any third party application that you use to connect to your computer? 
