In general, I have refrained from using Texture PEI plate for PETG for exactly the reasons you just learned the hard way. PETG is hyper-aggressive when it comes to sticking to surfaces but at the same time, it can still curl up at the edges if one forgets to add a brim. To me it’s somewhat of a paradox.
Two things I found helpful.
- Allowing the plate to cool before lifting the model helps but if you want to hedge that bet, freeze the plate for five minutes. The product will come off far easier that way. This also works if you forget and have to scrape off the material that is left behind like in your picture.
- Believe it or not, even though the Bambu plates say so right on the plate that it is for PETG I have found that the use of a glue stick can act as a release liner for PETG. The glued acts as a bond but it also becomes the layer between the two surfaces that will peel away much easier. Again, putting it in the freezer after print helps a lot.