Starting March 22nd 2022 and until August 23rd 2022
Find the Gremlin's Checkered Flag Check-In under the Event menu at the bottom-right of the game screen during the event period.
Reach the daily cumulative login time of 1 hour with character(s) at Lv. 50+ during the event, get the check-in stamp on the event UI, and press Receive Reward to get the reward for the relative cumulative check-in count
Attendance Check resets 9AM of each day, and attendance rewards are sent to your ID mailbox. If you didn't claim the previous day's reward, don't worry! It will be delivered to your ID mailbox when you log in after 9AM the next day.
If you miss a login day, you can make up for the missed check-in by using an item called 'Gremlin's Last-Minute Chance.