Turns out that if you have the cursor over where the chat will print the green text that on hover shows your dead body when you die, the 'death' and the 'death-camera' pop up at once, and you become unable to interact with the game in any meaningful way.
Testing with another member of the discord, jasmineheart, showed that this is a Singleplayer-only issue, as no matter the death or scenario, with the mouse hovering where the death camera text will be doesn't lock the game.
We only tested this in SA, but I found that it happens with seemingly any source of damage (demolisher, acid spitter, biter) that I did commit die with.
(Slightly related: Jasmine stated that the pop-up, if hovered over at the exact time of death, displays nothing instead of '0' for the death time. I have not verified this myself.)
[2.0.43] Singleplayer Hardlock w/ death camera
Re: [2.0.43] Singleplayer Hardlock w/ death camera
Thanks for the report. This is now fixed for the next release.
If you want to get ahold of me I'm almost always on Discord.