Do you have a reference for that? I'm genuinely curious since both terms are used in literature.

"combinatorial" was used predominantly in 1970s books for whatever reason.

In most of contemporary books and university courses "combinational" is used and with a note that you should not confuse it with "combinatorics" and "combinatory logic"

“An alternate term is combinatorial logic,[2] though this usage may be considered controversial.[3]”:

https://en.m.wikipedia.org/wiki/Combinational_logic