fps drop posting video

so I record my videos at 144fps and ive tried uploading them on tiktok through my pc but for some reason it just lowers the fps by a lot. so i tried instead sending the file too my phone and exporting it via the app editor named "VN". and when i uploaded it this way it gave the video 60fps and it lasted a couple of hours but then for some reason the video just dropped back down too like 30 fps?? im so tired of this how can other ppl upload such smooth high quality videos and i cant even share a video thats 60fps