I have the same troubles for a while also since Big Sur is coming… Three times today!
panic(cpu 2 caller 0xffffff8009f64a25): userspace watchdog timeout: no successful checkins from com.apple.logd in 120 seconds
service returned not alive with context : unresponsive dispatch queue(s): com.apple.firehose.io-wl
service: com.apple.logd, total successful checkins since wake (15530 seconds ago): 1542, last successful checkin: 120 seconds ago
service: com.apple.WindowServer, total successful checkins since wake (15530 seconds ago): 1554, last successful checkin: 0 seconds ago
iMac 21" Retina 4K 8GB RAM 2400 Mhz DDR4 (2017) Ghz Quad Core Intel i5
Radeon Pro 560 4GB
Any help possible or just waiting for an Apple Big Sur update/bugfix?