$ perl -MO=Concise,-exec -e'`...`'
1  <0> enter
2  <;> nextstate(main 1 -e:1) v:{
3  <$> const[PV "..."] s
4  <1> backtick[t1] vK
5  <@> leave[1 ref] vKP/REFC
-e syntax OK

$ perl -MO=Concise,-exec -e'qx`...`'
1  <0> enter
2  <;> nextstate(main 1 -e:1) v:{
3  <$> const[PV "..."] s
4  <1> backtick[t1] vK
5  <@> leave[1 ref] vKP/REFC
-e syntax OK

$ perl -MO=Concise,-exec -e'readpipe(qq`...`)'
1  <0> enter
2  <;> nextstate(main 1 -e:1) v:{
3  <$> const[PV "..."] s
4  <1> backtick[t2] vK/1
5  <@> leave[1 ref] vKP/REFC
-e syntax OK