MySQL date [plus sign / +] condition filtering problem

Today, I'm revising a SQL I found a problem about the time format when I was in school , primary SQL as follows （ It has been simplified ）

SELECT COUNT(*)
FROM im_first_statistics
WHERE prj_code IN('yxjt3311')
AND created_at BETWEEN '2022-07-20+00:00:00' AND '2022-07-20+23:59:59'

SQL There's no problem running , But the result of implementation is different from expectation .

Write a date comparison SQL, The results are as follows

Wondering if it could be MySQL Compare by string , When compared to + Greater than There will be no follow-up . Of course, this is an irregular way of writing , It's better not to write like this .