Unlock More Sabotage Quests With Variks - Complete A Hard Rain Falls (Destiny 2: Beyond Light)
If you are unable to buy any more quests from Variks, then you may need to complete the quest "A Hard Rain Falls". You get this from the Exo Stranger and it may be sitting in your inventory.
Upon completing the quest with Elsie and obtaining the reward, then you should be able to return to Variks and get more Sabotage quests.
