[66AK2H]SERDES routing restriction between Rx and Tx?

Dear Champs,

Is there any recommendation or restriction between TX line and RX line length of SERDES?

My customer want to check if these lines should be matched or it is OK to have small differential as much as 20mm between Tx line and Rx line.

When I checked it on the SERDES uuserguide, I could not find it and I need your help on this.

Thanks and Best Regards,

SI.