One user on the Discord had problems starting apps due to /run being full.
This is because logind limits /run to 10% of total RAM by default. profile-sync-daemon puts the firefox profile in /run, which will only get bigger and bigger until it fully exhausts /run and anything else that needs to use it will fail to do so.
Although increasing the maximum tmpfs size is one option, adding a warning makes sense since low RAM systems already have limited headroom and enabling psd can further exhaust available RAM.