Air bubbles in the transmission fluid and slippy when its cold
Air Bubbles in the Transmission Fluid
This is an indication of the transmission fluid level being low. This may be from a leak in the system or under filled at the last transmission service. The transmission fluid level needs to be checked when the engine is hot and running, the transmission is in park and the vehicle is parked on a level surface.
When the fluid level is low the transmission will indeed slip. Continued driving like this will damage the internal clutches. Repair as soon as possible to prevent any damage. If the fluid looks burnt it may already be too late and may require a rebuild. Top off the fluid level and test the operation.