This is a new temporary home office tax credit claimable for qualifying individuals who worked from home during 2020.
In order to be eligible a taxpayer had to work more than 50% of the time from home for a period of at least four consecutive weeks in 2020 due to the pandemic. The available claim is $2 for each day working from home. The maximum amount using the new flat rate method is $400 (200 working days) per taxpayer.
The detailed method is still available, but the new flat rate provides a simpler choice. More information at What the changes are – Home office expenses for employees – Canada.ca