RX560 works in PCI-E x8 and not in x16?

Question

Iron

Today I noticed in GPU-Z that Bus Interface: PCIe x8 3.0 @ x8 1.1

During the render test: PCIe x8 3.0 @ x8 3.0
The card is inserted into the PCIe x16 slot ASUS PRIME B350M-A
board Question: why does the card work in x8 and not in x16, what to do with it and where to run?

Answer 1

Any questions?

Answer 2

And what kind of processor do you have?
PCI-E x16 is connected specifically to the processor and there is a small caveat about this :

AMD Ryzen™ Processors
1 x PCIe 3.0/2.0 x16 (x16 mode)
AMD 7th Generation A-series/Athlon™ Processors
1 x PCIe 3.0/2.0 x16 (x8 mode)

Depending on the CPU, the slot may be x8 only.
However, the bandwidth for the RX560 should be enough anyway.