Per the title, R 3.6.3 is the last version of R 3.* and with it some packages are only built on 3.6.3+ (for example {dtplyr}).
Between R 3.5.3 and R 3.6.3 there were no major syntax changes (unlike with R 4.0.*), so will there be any Alteryx release built on R 3.6.3 assuming that you want to stick with major release 3?