Swift outflanking stratagem and strategic reserves rules

I've got a question from my opponent, and couldn't give a sure answer.

If your reserves die on turn 4, does it apply to your Raider or Venom put onto strategic reserves on turn 3 or later?
Btw I was reading the chapter approved GT 2020 strategic reserves section and didn’t find such a thing like dying on turn 4. Is it not a thing anymore in the 9th?

You know the only way I used the reserves in our old codex is deep striking on turn 2-3, so this whole thing is quite new to me.

Units held in strategic reserves at deployment need to be on the table by turn 3 or are considered destroyed.
Units put in strategic deployment from the table top are allowed to be put on in the next turn. (Like aircraft flying off the board).
The only time you should never remove a unit from the table to be put in strategic reserves is turn 5, as they are counted as destroyed because they are not on the table at the end of the game.

one of the most powerful stratagems in the new dex is swift outflanking.

I looked thru the BRB and couldent see the part where the units get destroyed after Turn 3. Do you have the page #?

Just started playing that they do not get destroyed because of my gaming groups inability to find the printed rule.

Hmm.
found this:

Quote :

Any Reinforcement unit not set up on the battlefield by
the end of the battle counts as destroyed.

so looks like there is no set round to be deployed. I will still look a bit and post if I find anything

Maybe it is in a FAQ? CA 2020?

I swear this was a rule, but could not find it anywhere.

Found it in the matched play section on page 282 BRB.

10. DECLARE RESERVES AND TRANSPORTS...
...in Eternal War missions, Strategic Reserve and Reinforcement units can never arrive on the battlefield in the first battle round. Any Strategic Reserve or Reinforcement unit that has not arrived on the battlefield by the end of the third battle round counts as having been destroyed, as do any units embarked within them (this does not apply to units that are placed into Strategic Reserves after the first battle round has started).

So our transports will never die on swift outflanking.
Thank you guys!