It stopped in 2018 and then got going again a year later. https://www.wilderssecurity.com/threads/seamonkey-releases.379481/page-2#post-2780899
FYI. SeaMonkey, Portable Edition 2.53.17.1 (internet suite) Released for the PA Platform, courtesy of PortableApps.com
FYI. SeaMonkey, Portable Edition 2.53.18 Rev 2 (internet suite) Released for the PA Platform, courtesy of PortableApps.com
FYI. SeaMonkey, Portable Edition 2.53.18.1 (internet suite) Released for the PA Platform, courtesy of PortableApps.com
FYI. SeaMonkey, Portable Edition 2.53.18.2 (internet suite) Released for the PA Platform, courtesy of PortableApps.com
FYI. SeaMonkey, Portable Edition Legacy XP/Vista 2.49.5 (internet suite) Released for the PA Platform, courtesy of PortableApps.com