Hello Guys, thank you for your answers,
I started with JDownloads 3.2, updated to 3.9, then the problem started,
Database Version 5.5.5-10.3.24-MariaDB
PHP Version 7.3.20
Joomla! Version Joomla! 3.9.21 Stable [ Amani ] 25-August-2020 15:00 GMT.
Arno, yes, I even try different browser, I use FireFox.
Many thanks, I think if the problem is solved in the next update I can wait, so I can avoid the rolling back.