It's not really a big problem. You should be storing arbitrary binary strings as blobs (and length() works properly with them), but the underlying encoding is nearly identical: https://www.sqlite.org/fileformat.html#record_format
Then DBMS should not allow to save a string that would make some function return wrong results. Either truncate with a warning on INSERT (MySQL approach) or better throw an error.
Note that this breaks a lot of core functionality unless you CAST(s as TEXT) before you use it, eg iirc LIKE won’t work. Then you’re back to the same problem.
