Don't use RAR
I sometimes joke with my TA Milan Petrović that his usage of RAR does not imply that he will be driving a rari. After all, he is not Devito rapping^Wsinging Uh 😤. Jokes aside, if you search for "should I use RAR" or a similar phrase on your favorite search engine, you'll see articles like 2007 Don't Use ZIP, Use RAR and 2011 Why RAR Is Better Than ZIP & The Best RAR Software Available.
So, why shouldn't we use RAR? The non-free license and Windows-centric aspects have already been addressed by Kyle Cordes in the 2007 blog post Why I do not use RAR. These reasons are still relevant; the official versions of rar and unrar are still non-free. There is an unofficial unrar that is free and open-source software, but there is no free and open-source rar as creating one is prohibited by the RAR license.
Let's address what else is new in the last 15 years and why the arguments for using RAR over open archiving and compression formats are long obsolete.
First off, 7-Zip achieves a better compression ratio, but it is much slower to compress than RAR. However, since 2013 Google's Brotli and since 2015 Facebook's Zstandard (Zstd) are two good options for file compression. Aside from the file compression, Brotli is well-supported in HTTP compression and Zstd is used in OpenZFS. They are quite competitive against RAR in terms of speed and size too: where RAR compresses a file to 318 MB in 100 seconds, Brotli gets 322 MB in 52.3 s, while Zstd gets 321 MB in 63 s (when 128 MB window size is used).
Furthermore, the small differences in the resulting file size matter less over time as bandwidth is increasing and increasing fast.
All things considered, there are no reasons left to use RAR.