A similar case on Microsoft Community mentioned a workaround, have a try.
Start Panneau de configuration --> Gestionnaire de périphériques
Select View --> Show hidden devices
Expand Computer --> Monitors*
Quand vous expand the Monitors vous verrez your current monitor (highlighted) and all the disconnected monitors (greyed out). You may see monitors with "non-PNP" and "PNP" listed aussi. Je crois these are aliases to your current monitor (at a lower resolution) before Windows installed drivers for it.
I uninstalled ALL the greyed out monitors. Faites un clic droit sur these monitors et sélectionnez uninstall. Keep only the highlighted monitor you are currently using.
After doing this my windows don't resize after my monitor goes to sleep. Vous pouvez quickly test this by temporarily setting your monitor sleep time to 1 minute.
Settings --> System --> Power & Sleep --> Screen [1 minute]
Source: https://answers.microsoft.com/en-us/windows/forum/windows_10-hardware-winpc/windows-10-multiple-display-windows-are-moved-and/2b9d5a18-45cc-4c50-b16e-fd95dbf27ff3
