I have the exact same issue and it's beyond frustrating. I had been using one external monitor (27" Dell P2720D) with the Macbook in clamshell configuration for almost 2 years, without a single issue with performance or any kind of crashing. I recently updated to macOS Monterey 12.2.1 and added a second monitor at the same time (BenQ GW2280). I wish I never made the decision to update to Monterey as I now cannot connect my external monitors with the Macbook without it going into a complete meltdown after a couple of minutes of use, resulting in a force restart. The only workaround I have managed to find is that it works perfectly if the Macbook lid is open. Meaning I now have 3 displays instead of 2. I really can't get my head around how the Macbook crashes running just 2 displays but can handle 3 without an issue! This problem has to be resolved as I suspect lots of users are having the same issue and just resorting to using 1 monitor thinking it's their Macbooks performance, not a software glitch. I also suspect some users aren't having this issue and it's going unreported as they have their Macbook lids open and their performance hasn't taken a hit. Apple, please, please, please fix this issue it's driving me insane! Macbook specs: MacBook Pro (16-inch, 2019) 2.3 GHz 8-Core Intel Core i9 16 GB 2667 MHz DDR4 AMD Radeon Pro 5500M 4 GB Intel UHD Graphics 630 1536 MB