When I have a DATE(TIME) column as a PK (or part of PK) and I try to SELECT a specific row using a datetime string which contains a timezone part, a warning is issued for "truncated incorrect datetime value" and the row is found.
When I try to do an UPDATE with the same WHERE condition, I get no warning, no error and the row is not updated.
When the column is not the PK, the UPDATE throws an error instead of silently ignoring it.
MySQL 5.6 seems to work without errors in http://sqlfiddle.com/#!9/9cffea/1 and https://www.db-fiddle.com/f/fA8ZG3px1XQdd8ANxCt6Xp/0
MySQL 5.7 and 8.0 on the other hand throw the error even when the column is the PK - https://www.db-fiddle.com/f/fA8ZG3px1XQdd8ANxCt6Xp/1.