The value of the Rotation parameter is outside the range of 0..360.

When the command is used repeatedly (/execute as @e[type=minecraft:armor_stand,sort=nearest,limit=1] at @s run teleport @s ~ ~ ~ ~90 ~), the Rotation[0] value of the armor stand steadily increases. Upon re‑entering the world, Rotation[0] takes on the corresponding value within the range of 0..360.