Just curious, which drawing app(s) did she test in?
It seems to be implied from the Samsung press release that the improved 2.8ms response time is software-based, and that it may require specific app-integration (eg. Samsung Notes):
The Galaxy Tab S8 Ultra and S8+ both come with a new and improved S Pen that uses a prediction algorithm for ultra-low latency15
15 Compared to Galaxy Tab S7. Latency speed of 2.8ms measured for Tab S8 Ultra(14.6’’) and Tab S8+(12.4’’) models when using Samsung Notes.
Judging from the language, other drawing apps may still exhibit the old 9ms response time. Alternatively, the improvements could be firmware-based on the digitizer, meaning the entire OS and application stack would benefit.
Hoping the latter… 