According to latest news of Serbian national broadcaster RTS, they announced the deadline for submitting a participation on 1st December of 2021!
It is most likely that Serbia will select their entry for Eurovision 2022 via a National Final. The only way this scenario cannot come true is a possible series of epidemic measures which will make the festival impossible to happen.
There is not a clear announcement that the national final will be Beovizija yet. Beovizija had been used by Serbia on six occasions in the past (2007-2009 and 2018-2020)
This mechanism of selecting the Serbian entry of Eurovision has been quite successful for the country in the past, since it had elected the winning song in Eurovision 2007.
The preceding winners of Beovizija in 2020 were Hurricane with the ethnic uptempo song Hasta La Vista.