Steam client is pretty bad. It's slow, full of ads, inconsistent, complex ... Its only quality is that everything else is worse and that it have an interesting ecosystem and ok tier customer policies (but that's unrelated to the software).
The thing takes several seconds to start on my brand new gaming rig. Not insufferable but given its only usefulness is to list my games and start one, that's a lot.
They have a proven unwillingness over many years to do what it takes to make Steam voice chat work reliably. It seems that their objective with Steam Chat is to do just enough to ensure that all Steam item-trading communication remains on their platform (for the worthy reason of controlling scamming).
The Steam client for starters but pretty much every game they initially released since 1997 was extremely buggy. They also struggle very hard to even release much anymore. I'll give them kudos on supporting OSS and their Proton development.
The thing takes several seconds to start on my brand new gaming rig. Not insufferable but given its only usefulness is to list my games and start one, that's a lot.