Some questions about outputting videos in PowerPoint

Question

Recently I have made an animation with PowerPoint. At last, the PPT file had 135 slides and lasted for 3:20 when using recorded timings. But after the video was output by PowerPoint, I found it difficult to upload the video to any website, because the video encoded in “MPEG-4” always had problems when converting to “H264” or other encoders (especially with ffmpeg). For example, some animations would disappear abnormally.

So I want to know, is there any way, such as plugins or VBA scripts, that can make PowerPoint directly output video files encoded in H264?

If the encode isn't "MPEG-4"but "AVC" from the beginning, what makes the problem happen?

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The file: https://1drv.ms/p/s!AsPsXBBUO0YC1ULwbdnjd2bUFP6h?e=JrTEtJ

The video which is converted and have problems: https://www.bilibili.com/video/BV1Ah4y1G7PX/ The problems are at 02:11 and 02:43