PTX10K with LC1202 based on our express silicon BT and it support 16K MTU and it runs on Junos-EVO where MX304 is based on Trio silicon YT, and it support 9600B with Junos. It is not Junos v/s EVO but purely based on ASIC capabilities and Trio 7 will support 16K on all interfaces.
Even though on document for MTU on PTX10008 do not mentioned version 21.4R3-S2.2-EVO it will support 16k MTU. On MX304 the transit MTU will be 16k.