Can somebody please tell me what it means when the 'class' icon above a player's head is flashing?

I don't mean the flashing 'heal me' icon, 'revive me' icon, or the flashing 'give me ammo' icon, I'm talking about when the player's own 'class icon' is flashing above their head.
So if the player is a scout, you can see their whole 'scout' icon flashing. These icons only flash for brief time but it happens often.

I've definitely seen it on team mates and squad mates, not sure about enemies, I've asked my squad about it and they don't know what they're doing that's causing it.

I assume it's providing some useful information but I can't work out what it means and it's bugging me now.
Does it mean they've been 'spotted' or 'suppressed', or they're reloading, are in the menus, are in their inventory?

I didn't find the right solution from the internet.
Hand Drawn animation