First go to Components, Akeeba Backup and click on Options, then Back-end. Check the "Date format". The default is
D j/n/Y H:i:s
If you have set up something different please try using the default.
On the same page you will see the Local time in Manage Backups. By default it's set to Yes. Keep that in mind for a minute.
All dates and times are internally stored in Akeeba Backup's database tables, just like everywhere else in Joomla, as GMT dates e.g. "2019-07-01 12:35:56" for June 1st 2019 12:35:56 pm GMT. When "Local time in Manage Backups" is set to Yes we pass that value into Joomla's JDate API and ask it to convert it to a human-readable thing
that's localised for your current language which, in your case, it's German. Joomla's JDate will internally use the language-specific override code shipped with the Joomla language package in administrator/language/de-DE/de-DE.localise.php and the translation strings in administrator/language/de-DE/de-DE.ini. If any of these has a bug the localised date string will look weird. This is what I see happening in your case.
The problem is that I cannot reproduce it with Joomla 3.9.8 and the latest German language package. When using the default date format I see "Di 2/7/2019 09:20:36 EEST" which looks correct.
If you have the latest German language package, Joomla 3.9.8, the default Date Format I told you about and you
still have this issue there is only one possibility: some third party plugin is overriding Joomla's JDate and making a damn mess out of it. I would start looking at translation extensions and their system plugins as potential culprits.
I hope this information helps!
Nicholas K. Dionysopoulos
Lead Developer and Director
🇬🇷Greek: native 🇬🇧English: excellent 🇫🇷French: basic • 🕐 My time zone is Europe / Athens
Please keep in mind my timezone and cultural differences when reading my replies. Thank you!