Basic support for the coordinate epoch of dynamic (not plate fixed) CRS has been added in line with relevant updates to GDAL.
QGIS has added support for respecting the source or destination coordinate epoch when transforming to or from a dynamic CRS.
If a dynamic CRS to dynamic CRS transformation at different epochs is attempted, which is not currently supported by PROJ, a user-facing warning message will be shown advising them that the results may be misleading and should not be used for high accuracy work.
This feature was developed by Nyall Dawson