At least in my case, wineserver: using server-side synchronization. gets printed for me when using wine-staging even when using WINEDEBUG=-all
I've never seen "wineserver: using server-side synchronization" using wine (8-15 and lower). Maybe it is different set of wine libraries?
I saw with wine staging, base wine doesn't show the message but I'm guessing proton is based on staging.
Hello!
wine respect export
WINEDEBUG=-alland suppress all output if enabled. But proton wine ignores this flag and keep spamming to the stderr even when this flat enabled :wineserver: using server-side synchronization. wine: RLIMIT_NICE is <= 20, unable to use setpriority safely
Proton uses patched wine. Those messages are added by Proton. The first message appears if esync and fsync are disabled somehow. The second message appears as it describes so. It is normal to be printed out those messages by Proton.
WINEDEBUG=-all`x3 2023-09
Hello!
wine respect export
WINEDEBUG=-alland suppress all output if enabled. But proton wine ignores this flag and keep spamming to the stderr even when this flat enabled :