PF2e: weapon hit randomly does half damage for no obvious reason

[laomedon]

I've been scratching my head over this one, trying to figure out why, seemingly at random, some of my players only do half damage on a weapon hit.
The game is Pathfinder 2e and we're playing the Age of Ashes campaign.

There are no defenses on the creature that would explain why a weapon hit only does half damage. And I can't figure out what's going on with the weapon or the player either. I don't see any reasons why it should be doing half damage, but it keeps happening and I feel like I'm missing something. It's pretty random. At one point one player was experiencing it more, another time another player was.

Has anyone had this issue? (And better yet, does anyone have a solution?!)

[stephan_]

Is the player using a specific push-to-talk key?

Edit: Alt seems to halve the damage (if a creature is targeted).

Do NOT use shift instead.

[laomedon]

Thank you! I just tested it and alt definitely made it half (and shift made it a crit).

I'll see if that's what's going on with them.

Thank you again!

[laomedon]

I've heard back from one player who thinks this is probably it. So thank you again!