The said bug is present only in multiplayer (including pure vanilla server).
It looks like only the 1st replay in the session gets "corrupted" this way. The presence or absence or other mods doesn't affect that.
Also, that loss is tied to the replay itself and the outer layer is lost even if litematica is removed after the recording.
Replay: https://www.dropbox.com/s/rak6l6d17w6p2r6
Replay from SP with working outer layer for the comparison: https://www.dropbox.com/s/hyqd47vmz6kw8o7
