Amidst the Pocophone F1 light bleeding debacle, Poco India released a statement explaining how it will help solve the issue and what's causing it. There's a number of users complaining about a backlight bleeding issue on their handsets. It also appears to be pretty widespread and hence the statement below. So according to the read above, just 0.3% of the units are affected by the light bleed and Poco India is encouraging its customers to visit their nearest service center. As for the rest of the handsets, Poco claims it's a software issue - a gradient color that may look like...
Source: https://www.gsmarena.com/poco_india_says_the_light_bleed_issue_plaguing_the_pocophone_is_a_software_feature-news-33652.php