Since this is built into the OS, your only options are modifying the app or modding the OS, neither of which are things I’m well versed in but here’s some stuff that can get you started if you’re feeling adventurous:
Modding the app: The way these actions work is android apps add a line in their manifest that registers them as handlers for “ACTION_PROCESS_TEXT”. Article on this.
I’d imagine you’d want to try and find a way to remove that registration from the app’s manifest. Couldn’t tell you exactly how but I know ReVanced lets you mod apps other than YouTube, so it could help with that?
Modding the OS: Since it’s built into the OS. If you can find the code that handles text selection actions, you could start with a custom ROM and add your own code that disables that action. Maybe even build a UI around it to help others with a similar complaint?!