Firefox and other applications keep crashing at the same

[cscs]

@Brot

Memory: total: 8 GiB
  available: 7.68 GiB used: 3.44 GiB (44.8%)

@Brot

Swap:
  Alert: No swap data was found.

You have no SWAP.
It is expected you will lock up when you hit the 7.68G of memory use.

You have a number of options for SWAP … I usually recommend zram these days.

Continuing the discussion from Awful performance since install:

@cscs

sudo pacman -Syu zram-generator

Then edit the configuration file. (use your preferred editor)

sudo micro /etc/systemd/zram-generator.conf

You want it to look like:

[zram0]
zram-size = ram / 1
compression-algorithm = zstd
swap-priority = 100
fs-type = swap

You may want to ensure zswap is disabled as well. One way is to add to the boot options, at /etc/default/grub the option zswap.enabled=0.
That is to add it to one of the CMD lines so that (Assuming no other options) it would look like:

GRUB_CMDLINE_LINUX="zswap.enabled=0"

Then run

sudo update-grub

And reboot.
You can check the configured swap/zram using

swapon

zramctl

PS.

@Brot

Kernel: 6.5.13-7-MANJARO

The 6.5 kernel is EOL. Please install 6.6, boot into it, and remove 6.5.