I have exactly the same problem on my laptop: IdeaPad 5 Pro 16 [Intel CPU + Intel Iris XE + NVIDIA GeForce MX450 +1TB NVME SSD].
I don’t have a solution but I have something which might set you in the right direction. I am writing this from memory so the details might be wrong.
The live version of Fedora Gnome didn’t have the blinking. I think Ubuntu live “safe mode” also didn’t have the blinking. I believe the reason is the GRUB options includes nomodeset in the “linux = …” line .
I didn’t manage to get the Manjaro live version to start with nomodeset. I admit I didn’t try very hard and have little idea of how grub works.
The other thing of interest is that when the display was working correctly, the display setting showed a refresh rate of 75? Hz.
It was not what cvt -r predicted!
For the time being I’ve delayed installing linux on that laptop. I hope this helps. Please share if you find a solution.