Can you clarify why you think it is 50%?

From the Instructions:

2020 Qualified Disaster Employee Retention Credit (Form 5884-A, Line 1b)

An eligible employer who continued to pay or incur wages after the employer’s business became inoperable because of damage from a 2020 qualified disaster may be able to claim a credit equal to 40% of up to $6,000 of qualified wages paid to or incurred for each eligible employee.

https://www.irs.gov/instructions/i5884a#idm139907417554336