Custom list formatting for entity reference fields.
Display field_tags as #Tag1, #Tag2, #Tag3.
Works for D10, but needs a patch.
Alternatives
This can be done in Views by rewriting the field as #{{ field_tags }}, however that doesn't help when you need to format the field on the display page.
A custom template could be created in the view, to apply to all instances of a field. That may be easier to handle, since this module requires configuring each field in every display mode.
Module page
Stability
Dev