Please note that if this was a Required Minimum Distribution (RMD) from your credit union, it is not eligible to be rolled over. According to the IRS, "Amounts that must be distributed (required minimum distributions) during a particular year aren't normally eligible for rollover treatment." There was an exception to this for the tax year 2020 due to the pandemic, but there is no exception in 2021.
If this is not an RMD, please report it as @dmertz outlined above. That will avoid taxation on any of the amount you rolled over as an indirect rollover as long as it was put back in the account within 60 days of receipt.
