Since 0.146, terms with default html output format are using the taxonomy.html template.
If used with a self-defined, html-based output format, the correct term template is used.
See the last two links of the sample page:
tags/one/index.html
tags/one/index.print.html
See
git clone --single-branch -b hugo-forum-topic-54317 https://github.com/McShelby/hugo-testing hugo-forum-topic-54317
cd hugo-forum-topic-54317
hugo server
While not ideal, my advice to theme authors is to forget about backwards compatibility. Either set the maximum version to 0.145.0 and leave things alone, or set the minimum version to 0.146.x and make the necessary changes.
I understand that this:
Won’t help those who have already installed the theme.
Will generate some noise.
Will require site authors to make similar changes if they have overridden any templates.