A bit tangential, but you are mistaken in that you are confusing container formats and codecs. MP4 is a container format, which can contain, among other codecs

A bit tangential, but you are mistaken in that you are confusing container formats and codecs. MP4 is a container format, which can contain, among other codecs, h.264 video. WebM is another container format, which can contain, among other codecs, VP9 video. MKV and AVI are other container formats, and h.265, VP8, and AV1 are other codecs. There are lots of codecs compared to container formats, and the same codecs can often go in multiple different containers (you can even convert encoded video losslessly to a different container format). Licensing issues are almost all around codecs, not container formats.