Some third-party programs use font attributes (e.g., strikethrough, double-underscore) to simulate the appearance of tracked changes. Click on one of the changes, then press Shift+F1 (Reveal Formatting). Is there a style applied with the name "DeltaView Insertion" or "DeltaView Deletion" or something similar? Another possibility: Someone could have used direct formatting to make the text look like tracked changes. If you can select the "markup" and press Ctrl+Spacebar to remove the formatting, then you know a character style or direct formatting has been applied. Cleanup? That's a different story. Sometimes reviewers apply strikethrough and double-underscore to portions of the same text.