Both are under active development and are used in several transcriptomics atlas projects, as far as I can tell.
Look at the packages now for integration, pseudo time, pseudobulk - R (and therefore Seurat) dominates heavily
It took a long time for Perl to go away from daily use in bioinformatics, solely dependent upon how common it was twenty years ago.
In our lab, there is me, a (mid career) polyglot who mixes Python, Go, Java, and R daily. I use tab delimited text files to transfer data. I also grew up coding in C++ and like learning new languages.
We also have a (mid career) staff scientist who grew up in Perl, but switched 100% to R and an (early career) postdoc who has always used 100% R. For both of these people, if work can be done in R, it is. If it can’t be done in R, they figure out how to do it in R anyway (even if that is shelling out to another program).
We also have a (young) grad student that is 95% Python. They try to keep to the Python tooling, even though they are quite aware of the R ecosystem.
There is a generational shift in the field, and it is more apparent each year. I find it interesting that Python took over from Perl first and now it’s trying to take over from R.
Maybe this is sub-field dependent, I'm a bioinformatician who hasn't touched R in about 5 years, and everything is now in python.