While looking at some unrelated issues in the d.org queue for Token 8.x, I noticed a new setting in the UI, which we don't have:

This seems to have been added only in the 8.x version, with https://www.drupal.org/project/pathauto/issues/2773573
GitHub Issue #:
4755
Recent comments
Hi. I use the "[node:title] | [site:name]" tokens for the main image of news articles, blog posts, and similar publications. It's a quick and practical automatic ALT.
How to Improve SEO Performance in Backdrop CMS
I understand how tokens work, but not so much their practical use in image alt/text (maybe caption?) text. Could you give an example or two?
How to Improve SEO Performance in Backdrop CMS
https://backdropcms.org/project/metatag https://backdropcms.org/project/xmlsitemap https://backdropcms.org/project/imagefield_tokens These are more powerful modules, in my opinion...
How to Improve SEO Performance in Backdrop CMS