Decimal fields behavior disturbing

Strange behavior when edit a decimal field with a number of decimal digits

If I delete 4 from for example 12,34 the field value becomes 1,23
If I add 1 from for example 12,34 the field value becomes 123,41

Many user complains on such unnatural behavior because they enter bills and no error is allowed.

I check the code and it seems that nothing as change since '17.

As someone already change de code of jquery.scInput2 ?? If yes can you share ???

Thx a lot