Oh, that’s a shame Netlify DNS is much more practical & flexible than what you get with .pp.ua. Nevertheless, I kind of solved the issue for now, but looking forward to any resolution on this thread!
Please, keep us posted
PS. The engineers working on this probably know that already, but just for the record, Mozilla maintains a public list of all shared domain suffixes, which can be found at https://wiki.mozilla.org/Public_Suffix_List. Seems like this might be useful for solving the issue.