Season passes are assigned to the account that logs in first. If you logged into Steam prior to cross save being turned on and after you had purchased the Deluxe Edition then the included season passes were assigned to your Steam account. Then you turned on cross save and selected your PSN account as the cross save account. This means your PSN account is the one being used when you log into Steam. Your Steam D2 content is now dormant in place of PSN which means the season passes are dormant as well. The correct assignment would have been to set up cross save first so that when you logged into D2 on Steam the passes would have been assigned to your PSN characters since under cross save your PSN account in essence would have been first to log in. Unfortunately there is nothing that can be done about the passes that were assigned to the Steam account as Bungie offers no service to transfer game content between platform accounts. The only option left to obtain all four season passes is to purchase the Deluxe Edition on your PSN account or link an XBox or Stadia account to your cross save and then purchase the Deluxe Edition there.