The Command makes nothing.

execute as @e[tag=spawn] at @e[tag=spawn] run gamemode survival @a[gamemode=adventure,distance=201..99999]

If I use

execute as @e[tag=spawn] at @e[tag=spawn] run gamemode survival @a[gamemode=adventure,distance=10..12]

it will work.

The chunk with the armor stand is at worldspawn