Today working on my favorite website - optionsbrew.com, for a moment I faced a small issue - how to display block (s) on the default taxonomy/term page.
I remember I was doing such tricks back in 2012 or 2013 and was wondering does it still applies in 2021, turns out - it does!
Here is the solution: on the Configure block page, under the Pages tab, enter /taxonomy/term/* and save
Configuring Drupal 8 block
Here is how our taxonomy term page looked before:
Drupal 8 default taxonomy term page
And here is after
Drupal taxonomy term page with custom blocks in sidebar
Hope it helps!