"convert" regression tests fail on PG 12..15

[df7cb]

On 1.8, the "convert" regression test fails on PG 12..15. PG 16 is fine. The diffs look like this:

--- /home/myon/postgresql/pg-store-plans/pg-store-plans.git/expected/convert.out	2024-02-02 05:36:28.000000000 +0100
+++ /home/myon/projects/postgresql/pg-store-plans/pg-store-plans.git/build-15/results/convert.out	2024-09-03 14:46:39.584046523 +0200
@@ -2285,180 +2285,180 @@
   pg_store_plans_normalize(lplan)
   FROM plans ORDER BY id;
 ### normalize        ###### Plan -4: some properties plus unknown key
-{"p":0,"l":0,"t":"a","t":"b","t":"c","t":"d","t":"e","t":"f","t":"g","t":"h","t":"i","t":"j","t":"k","t":"l","t":"m","t":"n","t":"o","t":"p","t":"q","t":"r","t":"s","t":"t","t":"u","t":"v","t":"w","t":"x","t":"y","t":"z","t":"0","t":"1","t":"2","t":"3","t":"4","t":"5","t":"B","t":"6","t":"7","t":"8","t":"9","t":"A","h":"o","h":"i","h":"s","h":"m","h":"I","h":"S","d":"b","d":"n","d":"f","i":0,"n":0,"f":0,"c":0,"s":0,"a":0,"o":"[]","m":"a","g":"p","g":"s","g":"h","g":"m","j":"i","j":"l","j":"f","j":"r","j":"s","j":"a","b":"i","b":"I","b":"e","b":"E","e":"h","e":"q","e":"e","e":"E","e":"s","k":"a","-":"a","=":"a","\\":"a","~":"a","|":"a","`":"true","{":"0","}":"0","ac":"false","5":"a","6":"a","7":"a","8":"a","9":"a","0":"a","!":"i","!":"d","!":"u","q":"a","r":0,"u":0,"v":0,"w":0,"x":0}
+{"p":0,"l":0,"t":"a","t":"b","t":"c","t":"d","t":"e","t":"f","t":"g","t":"h","t":"i","t":"j","t":"k","t":"l","t":"m","t":"n","t":"o","t":"p","t":"q","t":"r","t":"s","t":"t","t":"u","t":"v","t":"w","t":"x","t":"y","t":"z","t":"0","t":"1","t":"2","t":"3","t":"4","t":"5","t":"B","t":"6","t":"7","t":"8","t":"9","t":"A","h":"o","h":"i","h":"s","h":"m","h":"I","h":"S","d":"b","d":"n","d":"f","i":0,"n":0,"f":0,"c":0,"s":0,"a":0,"o":"[]","m":"a","g":"p","g":"s","g":"h","g":"m","j":"i","j":"l","j":"f","j":"r","j":"s","j":"a","b":"i","b":"I","b":"e","b":"E","e":"h","e":"q","e":"e","e":"E","e":"s","k":"a","-":"a","=":"a","\\":"a","~":"a","|":"a","`":"true","{":"0","}":"0","[":"x","]":"0","ac":"false","5":"a","6":"a","7":"a","8":"a","9":"a","0":"a","%":"a","@":"a","^":0,"+":0,"_":"a","!":"i","!":"d","!":"u","q":"a","r":0,"u":0,"v":0,"w":0,"x":0,"y":0,"1":0,"2":0,"3":0,"4":0,"A":0,"B":0,"C":0,"D":0,"E":0,"F":0,"G":0,"H":0,"I":0,"J":0,"K":0,"L":0,"M":0,"N":0,"O":0,"P":0,"Q":0,"R":0,"S":"d","S":"m","T":0,"U":0,"*":0,"Unknown Key":"Unknown Value"}
 
 =======
 ### normalize        ###### Plan -3: expression tokens 1/1
-{"o":["~?!?@?#?^?&?|?`???+?-?*?/?%?<?>?=?"]}
+{"o":["~?!?@?#"]}
 
 =======
 ### normalize        ###### Plan -2: all properties 2/2
-{[]"ac":0}
+{"V":0,"W":0,"X":0,"Y":0,"Z":0,"z":0,"#":0,"$":0,"&":0,"(":0,")":0,"_":"dummy","%":"NOTHING","@":"ia","^":123,"+":234,":":"system",";":["'10'::real"],"<":"'0'::double precision","[":"dummy","]":0,"ac":0}

Is this expected?