Steam weirdly closed itself like several times a day, then I ran it from command line via steam-runtime and this is what I got then it happens:
Installing breakpad exception handler for appid(steam)/version(1621394999)
Installing breakpad exception handler for appid(steam)/version(1621394999)
Installing breakpad exception handler for appid(steam)/version(1621394999)
Installing breakpad exception handler for appid(steam)/version(1621394999)
***** OUT OF MEMORY! attempted allocation size: 201326592 ****
src/tier0/memstd.cpp (2489) : Fatal Assertion Failed: OUT OF MEMORY
src/tier0/memstd.cpp (2489) : Fatal Assertion Failed: OUT OF MEMORY
src/tier0/memstd.cpp (2489) : Fatal assert; application exiting
src/tier0/memstd.cpp (2489) : Fatal assert; application exiting
Installing breakpad exception handler for appid(steam)/version(1621394999)
assert_20210603231939_178.dmp[425055]: Uploading dump (out-of-process)
/tmp/dumps/assert_20210603231939_178.dmp
_ExitOnFatalAssert
[deemon@Zen ~]$ assert_20210603231939_178.dmp[425055]: Finished uploading minidump (out-of-process): success = yes
assert_20210603231939_178.dmp[425055]: response: CrashID=bp-53e2ebde-86ad-46a0-93c9-ae21f2210603
assert_20210603231939_178.dmp[425055]: file ''/tmp/dumps/assert_20210603231939_178.dmp'', upload yes: ''CrashID=bp-53e2ebde-86ad-46a0-93c9-ae21f2210603''
Which is really weird as I have 32G ram and 2/3 of it was empty…