Altitude stuck at FL380 / V/S stuck at 5000

Hello everyone!

I’m currently flying on ES from Orly to Marseille with a stop at Biarritz and encountered issues with the A/P.

After departure from Orly, I set the altitude at FL350 with a speedy climb rate of 3000ft/min.
The A/P however decided to set the altitude to FL380 and the V/S at +5000ft/min.
I changed it back to FL350 but the A/P kept fighting me and set it back to FL380 on its own.

During approach at Biarritz and using VNAV to descent, the A/P once again ditched the descent and started to climb… again to FL380 with V/S set to +5000ft/min…

Without clues, I departed Biarritz and set sail for Marseille. Everything went good until I passed FL140 I believe (I’m still in the session) and the whole issue started again…

I figured out that LNAV/GPS is the issue. After disarming it, the aircraft stayed level and did not climb to FL380 anymore. Turning it back on and all problems start over again.
I almost stalled 3 times because of this.

What is really weird to me, in the same session, I flew to Cabo Verde as well and no issues during those flights. It all happened when I left Orly again this afternoon.

Am I the only one with this issue or are there others as well?

Playing on Iphone 15 PM, not sure which IOS, I believe 16…