MacBook Air M1 4k monitor connection issue after MacBook sleep or the unplugging the cable

My issue:

My MacBook Air M1 can connect to the 4k monitor and make the monitor display normally only after the first time I plug in the cable into the MacBook since restarting the computer or log into the account. If the monitor goes to sleep, or if I unplug the cable for the first time since it restarts or log in the account, even if I keep unplugging and plugging the cable, the display show no input detected. And I have tried using the "detect display" in setting, it doesn't work.

The apple adivisor has advised me to shut down the laptop and close the lid for over 30 second. I tried, the issue is the same. Their current reply is like, only the LG ultrafire 4k monitor is supported. I mean, they say only that one......

My setup:

I am using MacBook Air (M1, 2020, 8GB + 256GB) with macOS Big Sur 11.2.3 (which is the latest system by Apr. 19) and my external monitor is LG 27UL500, a 4k monitor. I am using a normal and functioning HDMI 4k 60 Hz cable with a hub from a third party called UGREEN from China.

Currently, what I know

1. For the hub, it is functioning normally with my previous full HD (1080P) monitor, which is Dell P2419H. But I don't have another 4K monitor to test the hub. So I assume it works well with 4k monitor since it supports 4k 60 hz via HDMI cable claimed by the manufacturer.
2. The 4k monitor is well functioning with PC.
3. The cable and hub is well functioning to connect my ipad pro 11'' 2020 to the monitor.

My solution:

After so many tests, to use the monitor after I need to unplug the cable or sleep the laptop, my only solution is to restart or log out and log in the account again every time. I also enable "Prevent laptop sleep after display off " option to keep the MacBook from sleeping.

I am currently buying a cable that directly conver type c to HDMI. Currently, I don't wanna spend money to buy apple official cable and hub because of the expense (I may do it later ). I don't wanna spend that much money to buy a new LG 4k ultrafire monitor as well (also because of the money).

What else can I do?? I am desperate.