Bought new Galaxy A25 in December 2025, was updated to One UI8 the same day. Since then experience 2 critical issues, the wi-fi signal degrade as soon as screen goes off (confirmed from ping response, even time-out noticed) and after that the apps dependent on internet experience delayed or  completely missed notifications until screen is unlocked and missed notifications appeared at once, even someone calling on WhatsApp doesn't show up when screen is locked. what I search so far is :

This is a One UI 8 Wi Fi idle / suspend regression, Specifically:
• Triggered when Wi Fi traffic becomes idle
• Activated after screen off
• Enforced by Samsung’s framework layer
• Ignored when the network is “chatty”
That is why:
• It works on busy networks
• It fails on normal home less busy networks
• Settings changes don’t help
• Re firmware doesn’t help

Currently device is with Samsung service center for more than a week.