Latest Facebook Messenger Lite 261 user agents:

User Agent Platform Device
Mozilla/5.0 (iPhone; CPU iPhone OS 13_3_1 like Mac OS X) AppleWebKit/605.1.15 (KHTML like Gecko) Mobile/15E148 LightSpeed [FBAN/MessengerLiteForiOS;FBAV/261.1.0.57.120;FBBV/210376599;FBDV/iPhone8 4;F iOS 13 iPhone 8
Mozilla/5.0 (iPhone; CPU iPhone OS 13_3_1 like Mac OS X) AppleWebKit/605.1.15 (KHTML like Gecko) Mobile/15E148 LightSpeed [FBAN/MessengerLiteForiOS;FBAV/261.1.0.57.120;FBBV/210376599;FBDV/iPhone12 1; iOS 13 iPhone 12
Mozilla/5.0 (iPhone; CPU iPhone OS 13_3_1 like Mac OS X) AppleWebKit/605.1.15 (KHTML like Gecko) Mobile/15E148 LightSpeed [FBAN/MessengerLiteForiOS;FBAV/261.1.0.57.120;FBBV/210376599;FBDV/iPhone10 5; iOS 13 iPhone
Mozilla/5.0 (iPad; CPU OS 13_3_1 like Mac OS X) AppleWebKit/605.1.15 (KHTML like Gecko) Mobile/15E148 LightSpeed [FBAN/MessengerLiteForiOS;FBAV/261.1.0.57.120;FBBV/210376599;FBDV/iPad11 2;FBMD/iPad;F iPadOS 13 iPad