First things first, check your z offset petg doesn't like being over squished and will lose adhesion because of it. The other thing you should do is ensure your surface is clean, depending on your surface a quick wash with soapy water and a brush is a good idea (some surfaces explicitly say not to do this, my buildtak surface called this out as something not to do), 99% IPA is decent at cleaning between prints but it's a good idea to periodically degrease your surface.
In my experience, adhesion issues with petg have almost always been due to residual oils (fingerprints) or bad 1st layer squish. I print in an enclosure, for me I absolutely require cooling, Prusa's knowledge base is a good place to start as well.