LG has reportedly delayed its first 42-inch OLED panels, extending the wait for smaller OLED TVs. The South Korean company announced that it would manufacture 42-inch OLED panels this year, but this now been delayed until 2022.
https://www.notebookcheck.net/LG-42-inch-OLED-TVs-with-4K-and-120-Hz-capabilities-delayed-until-2022.556545.0.html
Smaller pixels may well mean brightness will be challenged. Top emission panels (how long have we waited for those?) might be the answer. Many things remain to be seen so 2022 is probably just realistic. Don't rush a product out - that never goes well.