Adobe officially put Flash to rest on December 31, 2020. Overall, the end-of-life of Flash didn't cause a lot of issues as the bulk of the Internet runs on modern alternatives. It can cause some issues if you want to play old web games though. Furthermore, there are some old administrative tools as well as some educational software packages that still rely on Flash.
One of the big changes in Chrome 88 is the removal of FTP support. Google started phasing out FTP support in Chrome 86 and now it's no longer possible to make an FTP connection via the website. Users who relied on this functionality will need to install an FTP client like FileZilla.
Downloads over the HTTP protocol are now blocked too, file downloading is only possible via HTTPS in Chrome 88.
Google also made some improvements to its Dark Mode theme.