Today it felt like something was running slowly so I opened htop and saw a command called exe was using quite high CPU. But what is exe? It's a very suspicious looking name.

The PID for exe is 9645, so I can check where the actual executable is by looking in /proc.

$ ls -l /proc/9645
-rw-r--r--   1 user users   0 Apr  1 11:54 comm
-rw-r--r--   1 user users   0 Apr  1 11:54 coredump_filter
-r--r--r--   1 user users   0 Apr  1 11:54 cpu_resctrl_groups
-r--r--r--   1 user users   0 Apr  1 11:54 cpuset
lrwxrwxrwx   1 user users   0 Apr  1 11:54 cwd -> /home/user/
-r--------   1 user users   0 Apr  1 11:54 environ
lrwxrwxrwx   1 user users   0 Apr  1 11:54 exe -> /usr/lib64/firefox-latest/firefox-bin*
dr-x------   2 user users 241 Apr  1 11:54 fd/
dr-xr-xr-x   2 user users   0 Apr  1 11:54 fdinfo/
-rw-r--r--   1 user users   0 Apr  1 11:54 gid_map
-r--------   1 user users   0 Apr  1 11:54 io
....

So it looks like firefox 124 is calling itself exe for some reason? But htop also shows a lot of firefox-bin processes running too, so why would only some of them be called exe?
After restarting Firefox and reopening all the tabs and windows there is no sign of this exe command, and Google doesn't come up with anything helpful. So I guess it's a mystery for now.