Undocumented patch changes

[Olvan]

I had a mod pop up with synergy as a vendor special. (Sniper scope with scavenger)

Is this new? I've checked the vendors hundreds of times and today is the first time I've seen that...

[Nefarious]

No weapons with scavenger slots are in the game.

What is weird though is that weapons at vendors that I frequent had mod slots unlocked for some of my fav guns I would use and repurchase. Now thouse same guns have 1 to none mod slots unlocked from the start.

[Olvan]

The soleptor vendor sells 2 weapons with scavenger (a shotgun and smg)...

I've just never seen a mod with synergy for sale ever as a vendor special until today.

[Gleamwar]

There were available before the patch, just seem to be as rare as anything else you might be looking for.
It helps to hit all three ( that I know of ) hidden vendors since they have multiple specials in lieu of just one.
I make it a habit to run all the vendors a couple times a night to help increase my chances of finding something decent.

[Cavadus]

What is weird though is that weapons at vendors that I frequent had mod slots unlocked for some of my fav guns I would use and repurchase. Now thouse same guns have 1 to none mod slots unlocked from the start.

Did you just pass 1400 EGO? At 1400 you enter a new tier of weaponry. The mastery bonuses will be better but you'll lose mod slots. As you continue to progress in EGO you'll gradually earn those mod slots back.