How to wire a smart thermostat with dual Transformer system? R , Rc, W , Y , G. No C wire. No Jumper
You have a two-transformer system most likely
From the way your existing thermostat is wired, you most likely indeed have a two-transformer system.  This means that you will need a 3rd gen Nest, since the Nest E dropped two-transformer support, and the 2020 edition Nest supports the same physical connections as the Nest E.