I just installed the RStudio v1.4.1071-2 Preview. The console jumps around. Hitting "latest" does something, but doesn't solve it. Hitting escape a few times will stop it temporarily, but then it will start again after scrolling.
─ Session info ───────────────────────────────────────────────────────────────────────────────────────────────────────
version R version 4.0.2 (2020-06-22)
os macOS Catalina 10.15.7
system x86_64, darwin17.0
ui RStudio
language (EN)
collate en_US.UTF-8
ctype en_US.UTF-8
There are some known issues in the 1.4 console if you have enabled Preferences->Console->Limit console display to a subset of total content. That option was built to greatly improve console performance with a large amount of data in the console. The option was on by default until about a week ago in the 1.4 builds, but due to some bugs like the console jumping around, we have now turned it off by default for 1.4. With that option turned off, hopefully you won't have any console-jumping issues.