Older Android phones will no longer be able to see enough secure websites as of September 2021.
You may need to upgrade your Android phone and not upgrade to buy a new one if you want to visit secure pages that use https. According to Android Police, the certification company Let's Encrypt he warned that phones running Android versions before Nougat 7.1.1 will not trust root certificates starting in 2021.
The result will be that they will not be able to view enough secure web pages. The organization will stop on January 11, 2021 the default cross-signature for the certificate that allows this functionality and will withdraw its partnership on September 1 of the same year.
A temporary solution is available to install Firefox (Mozilla is a partner in Let's Encrypt) using its own certificate store, but this will not help other browsers or functionality other than browsers.
It is a habit for developers to abandon the support of older operating systems. Let's Encrypt noted that about 33,8 percent of Android users on Google Play have a version older than 7.1, and some hardware vendors cut support relatively early.
This means that you may have bought a low-cost phone in 2016 or even 2017 that could suddenly lose access to some sites, and without having a solution.