因為讓字串有顏色也是需要字符的啊～
沒猜錯應該是

control_node=$'\033'$'['0$';'33m''https://192.168.49.2:8443''$'\033'$'['0m
K8S_SERVER='https://192.168.49.2:8443'

echo $control_node
echo $K8S_SERVER

算字符數：

echo $control_node | wc -c  # 37
echo $K8S_SERVER | wc -c  # 26

你可以把黃色那個這樣測試

echo $control_node | cat -e  # ^[[0;33mhttps://192.168.49.2:8443^[[0m$
echo $K8S_SERVER | cat -e  # https://192.168.49.2:8443$

或者用 Python 看

echo $control_node | python -c 'print(repr(input()))'
# '\x1b[0;33mhttps://192.168.49.2:8443\x1b[0m'
echo $K8S_SERVER | python -c 'print(repr(input()))'
# 'https://192.168.49.2:8443'

#!/usr/bin/env python
# 注意這邊是 Python code!
control_node = '\x1b[0;33mhttps://192.168.49.2:8443\x1b[0m'
K8S_SERVER = 'https://192.168.49.2:8443'
print(control_node)
print(K8S_SERVER)

print(len(control_node))  # 36  # 因為差一個 echo 加的 '\n'
print(len(K8S_SERVER))  # 25