Have separately configured grafana image renderer, installed plugin and now can render any graphs.
But telegram alerts still without images and no any checkbox “Include image”
Grafana v8.4.6
Grafana Image Renderer v3.4.2
What should be configured else?
welcome to the 
forum, @falseclock
this took longer to implement than thought, but the ability is returning in Grafana 9. Check out the details here:
https://github.com/grafana/grafana/pulls?q=label%3Aarea%2Falerting%2Fscreenshots
Also see the lengthy discussion here: