Heya! 1Password employee here. We have never locked anyone out of their 1Password Account for missing a payment, and we never will.
Whenever your subscription lapses your 1Password account will instead go into a "frozen" state. While your account is frozen, you can still view, use, and even export all your items, copy your passwords, and even copy items to vaults outside your account.
The only things you won't be able to do while an account is frozen is add new items to vaults, edit existing items, invite people to your family or team, or autofill items in your browser.
It's common to see items temporarily go into that offline items list (sometimes only for a second) prior to it being synced to your 1Password Account, but as soon as that sync is complete, it should disappear from that list.
Are you only noticing older items in that offline items list, or are newly created items also showing up there? Likewise, if you search for the items you're seeing in that offline list in your 1Password Account, do you happen to see an entry that matches and contains the same information?
Whenever your subscription lapses your 1Password account will instead go into a "frozen" state. While your account is frozen, you can still view, use, and even export all your items, copy your passwords, and even copy items to vaults outside your account.
The only things you won't be able to do while an account is frozen is add new items to vaults, edit existing items, invite people to your family or team, or autofill items in your browser.