4Kbyte Limit

[Palingenesis]

I seem to have an issue reading/sending a web page I have saved to the Arduino NANO 33 IoT.
If the web page is over 4Kbyte I have to split it into small chunks.
Using the web server, when I return a web page I have created, I have to send it in chunks less than 4kbytes.
I have explained it in a video I made, go to about 21 minutes in, it's at the end of the video.
https://www.youtube.com/watch?v=YfYiSKDfy8I&t=47s

I tried to find info about data limits for the Arduino NANO 33 IoT, but I could not find any.
So I assume it is an issue.