Just to clarify, there are no “early” or later braisos. The vast majority were compiled by rebbe chiyah and rebbe oshaya, and these are treated the same as a mishnaj, just were left out by rebbe Yehuda hanasi(bra”ah, outside)
Some other braisos were in circulation and the gemara will rarely say that the braisoh was corrupted, but not in the main body of braisos from rebbe chiyah and rebbe oshayah.