Stealth and The Truth Effect on Jaw Sword

[(PSN)Crixus044]

I was looking at old game footage of me playing, and I noticed that during a truth syndicate effect going off, the gas damage made a yellow number, indicating either stealth or crit. I know it doesn't crit, so this must've been a stealth attack, which would make sense since the jaw sword is a melee weapon and melee attacks gain the stealth buff, but I thought the syndicate effect was separate from melee attacks.

Can someone confirm or disprove this, and/or explain why I saw a yellow gas damage number?

 

[Manyc]

I may be not speaking what matters, but may be of relevance.

Since a certain update, the syndicate procs no longer alert enemies, so they might be able to do stealth damage.

[(PSN)Crixus044]

54 minutes ago, Manyc said:

I may be not speaking what matters, but may be of relevance.

Since a certain update, the syndicate procs no longer alert enemies, so they might be able to do stealth damage.

I was using a sleep equinox on an eximus grineer sortie exterminate. I thought to use the jar sword to rank it up, so the stealth multipliers from the eximus affinity would max it out rather quickly, but i didn't take into account the aoe effect of the syndicate effect.