Issues with Timezone


I have 2 issues with timezone. I hope someone can help me.
My application is set with default timezone in Europe/Paris (UTC+2).

When I create an element, automatic fields created and modified are good : they register in the proper hour.
But if I have a datetime input, the time recorded is delayed by 2 hours. Example : in the field, I choose 16:00 and it is recording 18:00 in the database.

When I use a condition to display only the one with a publishing date in the past, I get a 2 hours reverse delay :
if a message is set in the database to be displayed only after today at 14:24:00, it is showing at 12:24:00 (and display 12:24 as the publish time).

So the 2 problems are cancelling each other out for the end user, but in the database, it’s a mess.

Does someone know how if it is possible to fix it ? And how ?
Thanks in advance,