The RX 6400 has acceleration for H.264, H.264, and HEVC decoding up to 4k. It does not have AV1, so it's highly situational where the RX 6400 doesn't beat out the new GTX 1630.
EDIT: The $150 is NVIDIA's suggested MSRP, I'm not aware of any actual cards selling for this (i.e. the Colorful is $170). I think where the GTX 1630 may have a market is in low profile settings. I'm not sure if the RX 6400 has a low-profile option. I haven't looked into it as I have no need for LP but I'm sure there are plenty who do.