Zebra plate! Not too bendy but also not very rigid either.
This plate seems to get better reviews for helping small prints stick better. Glad to see someone trying a larger print. Suggestions also recommend placing the “bow/rise/cup” down @ center, then clip-down the edges.
Is that what you are experiencing?
Instruction say not to use the heat bed for PLA but I find it necessary for large footprint 70c nice flat no warping
I know surface print bed flatness is essential. My setup has not been as flat as I want it to be but this zebra plate has been somewhat helping me with first layer sticking very well.
So far I’m very impressed