I am including a link below to publication 334 or the IRS which explains all the rules for independent contractors under the new tax laws. There are always questions regarding mileage and meals and overnight stays etc for mystery shoppers. The mileage info is on page 32 of this publication. From my reading of it we can still use the standard deduction from home to our first job, the mileage between jobs and then the mileage back home. I know it is too late for this tax year but you can bone up and adjust your record keeping accordingly for 2019.
[www.irs.gov]
[www.irs.gov]