Here are some things to try:

• make sure you have properly cleaned the new bed; ipa or dish soap. I have gone so far as lightly sand my new pei sheets with high grit sand paper to improve adhesion. Try the list below before considering sanding.
• bed temp: as you mentioned a cooler bed temp may improve corner curling. 50c or just yolo it and turn it off
• sounds like you’re printing with PLA: maybe slightly lower your hot end temp.
• mouse ears at the corners may help keep them from curling.
• make sure your printer isn’t catching a cool breeze.

Depending on the material, geometry, and print settings warping can be a big issue with 3d printing. In general you need more adhesion either by using glue, or by using a brim.

As others said clean the surface, but also consider bit more squish on the first layer.

Changing bed surface is a big change and requires calibration. First PID tune your bed heater if you havent already. Then find new good temp for your setup (assuming everything else is fine). To be fair, pla and pei are both quite forgiving, but having printer dialed in is almost mandatory for large prints.

I dont use pei, but printing on clean glass. 60 C with fans off is perfect for 1st layer, but then I have to change it to 56 C to avoid corner lifting on large prints.

Also good practice is to leave printer heated for like 20 min before you start printing

To echo others, make sure your print surface is clean and oil free, soap and water with a gentle scrub is good maintenance (unless your surface explicitly says not to, buildtak came with a big warning to only clean with IPA) and absolutely avoid things like acetone to clean it, IPA is alright to clean between batches.

I've not seen pla lose adhesion like that, Do you have some pictures of what your first layer tests look like? Curling I've seen when your nozzle is too close to the surface, some of the worst adhesion issues I've had are because of that specifically on petg and somewhat on abs. But try to eliminate one variable at a time, get your surface oil free and then check your first layer again.

Does it happen everywhere or just on the edges of the plate?