Description of the need Some tokens are missing from Backdrop and D7 core. This issue is addressed here https://www.drupal.org/project/token/issues/691078 and is considered major. Maybe all the needed tokens are already included in the Entity Tokens module which is now available in Backdrop contrib.
As an example I'll present here some tokens available in D8/D9 about forums which are missing from Backdrop core. Though, Entity Tokens provides availability of most of them if not all. We just need to check if there is anything not covered by the Entity Tokens module and if this module should be part of the core.
Please see in the attached photo what taxonomy tokens Drupal 9 now offers

Recent comments
@yorkshirepudding, In the end I fixed it by deleting the config/active folder contents, copying the config/staging/ files into config/active, importing the database again and clearing the caches...
Importing the staged config throws an error: another field with the same name already exists
Thanks, I have to go out now, I will try later on and report back
Importing the staged config throws an error: another field with the same name already exists
Hi Francis. Yes, what config do you have in staging for it? You might have configs like: field.field.field_video_embed field.instance.node.page....
Importing the staged config throws an error: another field with the same name already exists