Starting from macOS 15 (Sequoia) in the autumn of 2024, macOS has a standard feature across its editors that provides auto-completion of mathematical expressions. These look like as follows

This suggestion will then be entered into the editor if a tab key is pressed. It can often be less than desirable to have such an expression auto-complete to the most obvious choice when the writer wishes to carry on writing what they had in mind. We’ve therefore added a setting that allows the user to switch this behaviour completely off. Please see the new setting as option Use math expression auto-completion in the Editing Aids pane of the Preferences window; a screenshot is shown below,

Th new setting has been a response to user requests and will be introduced in Texifier macOS 1.9.28.