I have a feeling this is more likely youtube's fault than Voukoder, but I thought I'd post it here just in case voukoder or x265 is doing something weird causing this. Basically, for the last three 1080p SDR x265 10bit videos I've uploaded to my youtube channel, when I first upload them, I would find random spots in the video where it freezes for a few seconds, and then resumes playback. The first time, reuploading was able to fix the issue. The second time, I contacted support, and they were able to re-process the video, and it worked fine. Today I just uploaded another and had the same issue. The videos play fine on the computer.
YUV 4:2:0 10bit
Everything else default. I used 10bit because I'm doing HDR-to-SDR color grading and I want Premiere to process everything at full bit depth to avoid banding, and since I'm using 10bit, I'm using x265 for that. I believe my most recent 4K HDR video processed correctly, but it's possible it had the issue too and I forgot. I know for sure it was happening on my 1080p SDR videos though. The first time I noticed this was in November, which was my first upload in this format since July. That one worked correctly, as did the 4K HDR uploads I uploaded in September.
EDIT: I remembered that the time I reuploaded to fix it, I had remuxed to MP4 first. I just reuploaded my MKV hand had the same issue, so I'm going to remux and reupload the MP4 version. Perhaps an issue with the MKV container? Will update after uploading MP4.
EDIT 2: MP4 appears to be working fine