Probably those other people choose manually a mp4 render template according their project settings, this still works fine in build 179. Only the "automatic" MP4 render option produces a bad quality mp4.

@3POINT, can you help me understand how to do this? I followed the tutorials to manually set up render settings, same problem. A 4K video rendered with v.16 is 1.81 GB. The exact same file being rendered at 89.9 MB (yes, MB) with v.17. I adjusted manual settings. I uninstalled and reinstalled (frustratingly, Build 179 reinstalled itself.)

Just saw your question today, maybe too late to answer, but anyway here's the temporary solution. In my example I used a 2160p50 clip from my DJI Osmo Pocket. Just don't use the "automatic" MP4 renderoption but go to advanced options and follow the instructions in screenshots below. The result is a MP4 render file with adequate bitrate and quality.

@David-Hancock @Daniel-Sills you may want to go back to build 143 for the moment (advice here). See this comment from VEGASDerek.

Is there an updated link? The 143 build keeps giving me a void error every time I try to open it.