Also, I tried this on your forum and it works.

I use topic tags in power search often, and I have no issues with it, and no other user has reported similar issues. Open a new topic in the support forums: https://support.dev4press.com/forums/forum/plugins-lite/gd-power-search-for-bbpress/ and include more information and screenshots of what you are trying and what you expect to happen but it doesn’t.

I used the bbpress forum, it is supported by your plugin. But I still cannot search the topics tags

Please, use support forums, include more information about what you trued to do, including plugin version.