found a solution to get the interaction running as usual.
I found that it is related to “transactional file locking” topic. Do I have the code in my config.php included according to Nextcloud docs then I receive RedisException connection refused or RedisException no such file or directory. I am running NC on a shared host with cPanel beneath. I now raised a ticket at my provider. No idea if they provide Redis as a running service on their servers.