Vault (password manager) data are critically important and can't be lost, losing vault data is losing all access to all things.

Some vault software such as Bitwarden has the permanent storage even for inactive accounts, and that's the supposed-to-be way.

There are these 2 situation:
- User using both Proton Mail and Proton Pass
- User using only Proton Pass

For the first situation
- User will access email everyday and the inactivity rule never applies
- And thus Proton Pass data are sure there

For the 2nd situation
- User may use Proton Pass for access, eg. web
- But there is a case that all sites are authenticated
- and even for a year (may happen), no need to use Proton Pass
- Now it's inactive and the vault data are deleted

Losing vault data as said above is disaster,
I guess Proton account should not be closed due to inactivity,
data of other Proton apps can be wiped due to inactivity,
but Proton Pass must be permanent.