It looks like Textual has now been sunset and is essentially dead :

Please take notice: Textual has been formally sunset and this is likely to be the last update to be made available. To all that have contributed to Textual in some form in the past; be it a suggestion, bug report, financial support, or some other form of contribution, you will forever be loved. Thank you so much. Words cannot properly express the gratitude we have for every single user.

It was a really good IRC client, but it did not get the love it needed for quite some time now. I guess the user base wasn’t really there anymore to warrant any serious development on it.