Here is a nicely worded article:

"The new tax law changed the deadline for repayment after you leave your job starting in 2018. In the past, you generally had only 60 days to repay the loan or else you’d have to pay income taxes on the money as if it was a withdrawal (and a 10% early-withdrawal penalty if you left your job before age 55).

But under the Tax Cuts and Jobs Act, you don’t have to pay taxes or the penalty if you repay the loan by the due date of your tax return for the year when you leave your job (including extensions). For example, if you leave your job in 2019, you’d have until April 15, 2020, to repay the loan (or October 15, 2020, if you file an extension)."

https://www.kiplinger.com/article/taxes/t001-c001-s003-ex-workers-get-more-time-to-repay-401-k-loans...