/execute Command Blocks no longer work after ~1.19

All command blocks with /execute made before ~1.19 with experiments on worked in that time but, after the update, despite having proper syntax, throw an error e.g. "Unexpected "as" at /execute >>as<< @e[type=..."

Steps to Reproduce:

1. Make a command block before ~1.19 with "upcoming creator features" on
2. Add a "new" execute command (execute as, execute at etc) and turn on "last output"
3. Update the game
4. Open the command block's UI

(not possible for mobile anymore, which I was using)

Observed Results:

It throws an error

Expected Results:

It should not throw an error

Notes:

I am not exactly sure when this happened, but I think it was 1.19. Tested this by turning on and off and cloning with a structure block. An error was still thrown. I spent a lot of time on a command block thing using the execute command and it doesn't work anymore, I do not want to re-make the whole thing. Just to check, I ran a simple "/execute as @a run say test" at the same time and that worked for some reason.

These commands were all different, but most of them follower the structure "execute as [target] at @s run [command]