Video appeared where it looks that the X-101 uses heat traps during the recent attack on the UkroReich.Since this is new to me, can't find anything... I'm posting this comment found sounding more knowledgeable:

Aircraft's use those and called chaffs/decoys/flares. But using those in missiles is kind of new technology being demonstrated.

adding this...

Our X-101 missile has learned to shoot decoys for MANPADS and other air defense systems in service with the Ukrainian Armed Forces.