Safari 15 has been released on 20th September 2021 for macOS Monterey, macOS Big Sur, macOS Catalina and iOS 15.
Apple users have reported experiencing issues with multiple sites whilst using Safari 15.
We have checked this version and have found that mashme.io may not work correctly at this time.
We will monitor future Safari upgrades to check if Apple has resolved these problems.
In the meantime, we recommend you not to upgrade Safari to version 15 or to use another supported browser.