After update, apps aren't downloaded

have the same issue.
after upgrade i lost contacts and update is not working.
sudo -u www-data php occ app:install contacts
Error: Could not download app contacts

since 20.0.1 i have to manually download and install.
my configuration is behind reverse proxy and was working well before version 19
it is getting worse after each update.
wondering is a complete new setup is the only option

Sorry, this wasn’t really related, so I put it in a different thread. Reverse proxy setups are a bit more tricky, does the server have a direct internet connection? Logfiles?