Try to look up the challenges in the link below

Monomad challenge: @monochromes/monomad-may-25th-please-read-the-contest-rules-before-submitting-your-images-qawccl

Photo filters contests: /trending/createthatlook

Red Fish rally: @theterminal/redfish-rally-500-goal-setting-challenge-week-4-may-25-31-2020