Images/icones not showing up

Nextcloud version (eg, 18.0.2): 19.0
Operating system and version (eg, Ubuntu 20.04): Linux 4.9.0-0.bpo.12-amd64 x86_64
PHP version (eg, 7.1): 7.4.6

Hi team,
I have two NextCloud install: version 18.5 and just now 19.0 and I am facing the same problem:
some images or icone (don’t know the exact name) are not showing up as per examples below.
Any chance I could now why?
I have to add that this is the same problem on my phone using NextCloud app on Android.
Also still on my phone, when I click on “Send a file”, nothing happen…

Edit: version 18.0.4 works like a charm only if I use automatic the package installer from my web host, but I have the same problem than above, if I do the install myself (send file to ftp, create data base…) with any NextCloud version

Thank you