There seems to be a problem with Maxthon PC 7.3.1.6800 beta and TikTok.
If you open some channel on TikTok and click on some video, there will be a "Floating Player" icon in the lower right corner of the video. If you click on it, the video opens in a new "floating" windows. However, this window can't be closed even if you click on the X in the upper wight corner of the window.
In Edge browser and Chrome browser I did not observe this issue.