Jitter on the outbound leg only

Hello, everyone.
I have random jitter only on the outbound leg. The incoming traffic is perfect without jitter. Can any Asterisk of Linux setting cause problems?

That’s not possible. It is more likely that the jitter is being reported incorrectly.

That’s what Whireshark shows. I have listened to some streams. I think, indeed there are some errors in Whireshark, because in one example several channels (calls) were mixed, but the recordings were OK.