Thanks!
I’d say that the solution in all cases is to find whatever the app’s “paste without formatting” command is and use that on a regular basis. We really should be doing that every time we go from the web to a word processor. Otherwise there is no end to the junk you will end up migrating.
As a side note, the SC browser extension has a few features related to copy and paste from SuttaCentral. There is a key to copy all visible text just as text. And one to toggle selection of only one language (so you can just copy, for example, the English without selecting the Pali).