At this point in time, it's reasonably healthy to assume that everything has backdoors. The only place where information can be kept safe and hidden is deep within our minds. Any method used to share said information with another human being is subject to surveillance and backdoors. Only share what you don't mind being read by the state and it's friends.
If you want to apply this advice practically, instead of using and trusting any of the various password managers out there, use a brain-stored hash algorithm for all password management. For example your hash could be <some secret phrase> + the last 4 letters of the website/service being visited, with the last 2 letters flipped. Combine the phrase in some non-intuitive way.
Only other considerations are to have a more basic hash for certain financial websites/insurance companies (cough Allstate) that for some reason think an 11-character max password is still okay in this millenium, and to have a method of "incrementing" the password in case you have a service that forces rotations. The only reason to write the hash down is for financial service access in the case of estate planning - store it securely/safely, of course.
Ever since switching to this, I've found it's even more convenient than a password manager. You get used to running your hash in a very short time, and don't need to have access to an electronic device to recall a password.
I had thought of doing that but the various differences and requirements for password length and characters everywhere make it difficult to standardize on one hash. Before you know it you're keeping track of different hashes and it becomes risky to memorize. Or is your experience different?
