Re: Data problems after uplift from version 5.1.49 to 8.0.23

[Peter Brawley]

Through 8.0, MySQL auto-suppresses .0 in float results ...

drop table if exists t;
create table t ( f float);
insert into t set f=7.0;
select * from t;
+------+
| f    |
+------+
|    7 |
+------+

https://dev.mysql.com/doc/relnotes/connector-j/8.0/en/ reports just two changes in the connector's handling of floats, neither of which mentions the change you observe.

So it appears you've found a bug or a documentation error, consider reporting a test case to bugs.mysql.com.