Consiglio: If you are filling out an ‘anonymous’ employee satisfaction survey at your work, especially one with comments, fill it out with the assumption that it is not in fact ‘anonymous’

This is true even when a company uses a third party system and genuinely makes an effort to make them anonymous.

How they typically work. You submit your results and comments. Either the third party or HR gets them and organizes them by org/team/manager. Management then gets the results of their team. The results are anonymous in that they don't have names attached however, if free written comments are a part of it, your direct manager (assuming they are not an idiot) can usually easily tell who wrote what comment just by way of knowing you, how you communicate, etc.

Edit: to clarify, this isn’t an opinion as to whether you should or should not fill them out. I actually always do and am usually pretty honest in my feedback. The point is more to do so with the assumption that it is not actually anonymous. In other words, if you’re not comfortable giving said feedback to your manager directly, then maybe don’t put it in there.

Also, someone mentioned things like sexual harassment complaints etc. this has nothing to do with that. I’m only talking about those dumb employee surveys businesses like to do so they can pretend like they are ‘listening’. Sexual harassment complaint anonymity is a whole legal issue. Not related.