After installing the latest firmware, I have a similar problem. I formatted my drives, a very long process 4 TB) and once it finished I created a share and assigned the existing user. The newly created share could not be accessed from macOS Ventura. Only when I changed the access right of the share to Public I was able to access the share. I will downgrade.
I identified that the issue was the macOS. I removed all entries in the keychain that pointed to the NAS. There was also an entry for the time machine that pointed to the NAS, I believe it was the culprit.