What have been your personal experiences fighting against or GMing with lesser deaths and the Grim Reaper, post-remaster?

Earlier, I played through four attempts at trying to fight the 21st-level Grim Reaper in Path/Starfinder 2e. We suffered four straight fails. It is still an egregiously overpowered monster that punches far above its printed level and XP value.

Of course, we still have the strange scenario wherein an equal XP value of 16th-level lesser deaths is significantly more dangerous. They are even stronger for their printed level and XP value.

What have been your own experiences with these monsters?