In Turkish de/da can be a suffix or a conjunction or of course a part of a word. If de/da is used as a conjunction you have to write them separately. If it’s not written correctly it can be confusing for those who are reading the sentence.
Example 1:
“Bende gittim” instead of “ben de gittim.” (I’ve gone too). “Ben de gittim” is the correct sentence. De means too in this example.
Example 2:
O da iyi (It is good too). “Da” means “too” in this sentence. Oda iyi (The room is good). “Oda” means “the room”. Odada iyi (It is good in the room). 2nd “da” means “in”. Oda da iyi. (The room is good too). 2nd “da” means too. Odada da iyi. ( It is good in the room too). 2nd “da” means “in”, 3rd “da” means “too”.