PCI-e v4 card on PCI-e v3 board Performance loss?

Technologies ; Additional Features, PCIe, Gen 4, Gen 4, Gen 3 ; NVIDIA Encoder , Gen 8, Gen 7, Gen 7

After a quick Google search, I found this article which explains that: a PCIe x16 slot can theoretically hit approximately 32 gigabytes

pciex4 slot Currently, even the fastest graphics cards from Intel, AMD, and Nvidia still utilize the outdated PCIe standard Sure, you can pair them with a PCIe Gen 5

pcie m2 slot 4 GPU passthrough Blacklisting drivers; How to know if a Some motherboards can't pass through GPUs on the first PCI slot