The problem here is how the extra premium is defined and on what scale. There are numerous variables when it comes to underwriting strata insurance and this scenario could be applied to commercial tenancies which may attract a higher rate of premium. It is unusual that a strata insurer would blatantly increase a premium by 25% because of a few short term lettings or an Airbnb and insurers do have a tolerance for such matters when they rate the property in the first place. I have never come across that scenario before and if an insurer dictated an increase in premium for a portion of short termers I’d get it removed, look at an increased excess option for short termer claims or use another insurer. Some insurers do not even ask about short term rental/holiday let or Airbnb.