Ready to deploy your service/product on-prem environment. The main problem with on prem deployment is maintaining multiple versions. try to make sure you have better test coverage from day 1. in saas its easier to push the changes but on prim setup even minor update will take months from taking approval to deployment.
In my case i observe this was happening because of keyboard i was using (Gboard in my case), generally they keep track of all the words we are typing (for dictionary or suggestion purpose??) and that is used for ads targeting.