I'll have another look at the alert system's auto-decrease but it should be fine. The decrease rate is very slow to encourage you to not cause alerts in the first place. I may also implement other ways to decrease it in the future or ways to recover sealed lockers. Also note that the alerts are depleasted when an officer is sent out. You can also grab or gas that officer to make sure they do not seal a locker.
The upgrade system cost increases at around every 4 or 5 unlocks so that you have more choise of what to unlock before other upgrades presented. If I changed this to a static system it would not be any cheaper to unlock later upgrades. Note that unlocks (new infections types for example) will be more expensive than the upgrades. For ex, if thge upgrades are currently 5 then the unlock could be 9 or more.