A friend of mine started facing this problem yesterday night: when she browses through her Instagram stories, the video plays at a slower rate than normal, however the sound is totally fine. She went ahead and checked the gallery as well - same problem there. In TikTok though, there are no issues at all.
As she did not provide any more information (she is not tech savvy at all) here is the info that I know about her phone: it's a Huawei Y5 2018, with Android 8.
I searched online about this, but I didn't come up with anything related to Android. Any help is appreciated.