Sorry... maybe this question is really really dumb, but maybe we just don't know yet?

What is a Strain Token? It's not a Stress token, is it?

And what does it do?

It was in the Separatist Squadron Pack Upgrades article:

"[...] a strain token, making it even more vulnerable to attack—while a strained ship defends, it rolls one fewer defense die. A strain token is removed after a strained ship defends, but it’s far better to remove the token by executing a blue maneuver before being targeted while at an extreme disadvantage."

https://www.fantasyflightgames.com/en/news/2019/1/18/power-and-profit/

Additionnal question which may not have an answer yet but I submit it anyway :

If I'm stressed and strained, and I execute a blue maneuver, what happens ? Do I remove both red tokens ? only one ?

Both.

Probably.

59 minutes ago, thespaceinvader said:

Both.

I’d say it’s more likely to be only one, given that a blue maneuver only removes one stress at a time.

1 minute ago, DexterOnone said:

I’d say it’s more likely to be only one, given that a blue maneuver only removes one stress at a time.

True, but I would imagine they're not going to want to retroactively change the rules for stress tokens - which means that the (new) rules for strain tokens would be independent of the rules for strain tokens, meaning "removed after you defend or after executing a blue manoeuvre", which would mean, as @thespaceinvader suggests, probably both.

New rules in 1.0 tended to be 'bolt-ins' which didn't change existing mechanics.

Mm I would expect them to be independent and parallel, I.e. each blue removes 1 stress and 1 strain.