DDR4 and DDR5 do not mix.

No. Not in the same laptop, not ever. They are electrically incompatible.

DDR4 and DDR5 use different pin layouts, different voltages, and different signaling protocols. Even if the physical slot looked the same (it’s not—DDR5 has a different notch position), the motherboard memory controller is designed for one generation only. Soldered RAM is locked to that generation.

So if your laptop has soldered DDR4, you cannot add a DDR5 SODIMM. And if it has soldered DDR5, DDR4 won’t fit or work. You’re stuck with whatever generation is soldered.

Don’t try to force it. You’ll just waste money and possibly damage something.