Apple used the model identifier A1278 for six different sets of MacBook Pros, released between Late 2008 and Mid 2012. In 2011, there were two 13" MacBook Pros (Early 2011, Late 2011) – but for both, High Sierra is the end of the line.
If you're not running it already, you may want to install Firefox 115 ESR. It no longer gets new features, and it won't be receiving even "critical security updates" for much longer, but it might let you browse some Web sites that pose issues for High Sierra's old version of Safari.
Mozilla Support – Firefox users on macOS 10.12, 10.13 and 10.14 moving to Extended Support Release