Same here as well. Has happened about 3 times in the last 24 hours - always when I'm away from and not using my computer
Big Sur 11.2.1
iMac (Retina 5K, 27-inch, 2017)
Processor: 3.4 GHz Quad-Core Intel Core i5
Memory: 8 GB 2400 MHz DDR4
panic(cpu 1 caller 0xffffff800dd64a25): 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.drain-mem
service: com.apple.logd, total successful checkins since load (50620 seconds ago): 5051, last successful checkin: 120 seconds ago
service: com.apple.WindowServer, total successful checkins since load (50560 seconds ago): 5056, last successful checkin: 0 seconds ago