No button, only a hyperlink

Hi, I have this widget installed and activated in my sidebar but for some reason there is no button displayed. There is instead a hyperlink to my twitter page.

Strangely though, if I view my page in the browser on my mobile phone, it is indeed a button. On my PC there is only a hyperlink – both in firefox and chrome browsers.

https://ww.wp.xz.cn/plugins/bibs-twitter-follow-button-reloaded/