4.2.2 means the recipient's mailbox is over quota. It is temporary and the address is still valid, so retry. If it persists for several days the mailbox is likely abandoned and should be suppressed.
What it looks like in the log
452 4.2.2 The email account that you tried to reach is over quota.
452 4.2.2 Mailbox full
552 5.2.2 Over quota
Why it happens
The recipient is not reading or clearing their mail.
An abandoned mailbox that is still accepting connections.
What to do
Retry on the normal backoff schedule for a few days.
Suppress after a sustained period. A permanently full mailbox is an unengaged recipient and often becomes a spam trap.
Note the 5.2.2 variant is permanent: same meaning, different verdict.