Did you test on both versions of blender on the same day? It is possible that it was because of some driver update.
It would also be good to check with factory setings (File -> Defaults -> Load Factory Settings) to make sure it is not a configuration.

I have tested both versions at the same time. The problem comes in the configuration of the "Tablet API", in automatic mode it does not detect the tablet. Changing the setting to "Wintab" within "Tablet API" the tablet works fine. In 2.91 automatic mode works well.

So the problem is that the "automatic mode" configuration no longer detects the tablet.
This looks like a regression.

@Nicholas Rishel (nicholas_rishel), since you are more familiar with this area, do you know what may be happening?

@Daniel Molina Marchán (Theodet) could you repeat the bug in this build, copy the system console to this link, and link the paste in a reply to this report?

Most likely the driver is not correctly reporting the number of connected devices.

In this build it also gives the same bug. For it to detect the tablet correctly, you have to change the "Tablet API" to "Windows Ink" and then back to "Automatic" or "Wintab".

https://developer.blender.org/P1902

@Daniel Molina Marchán (Theodet) updated build with better logging, and paste link.

https://developer.blender.org/P1920

@Daniel Molina Marchán (Theodet) another build, paste link.

In T84728#1098317, @Daniel Molina Marchán (Theodet) wrote:

In this build it also gives the same bug. For it to detect the tablet correctly, you have to change the "Tablet API" to "Windows Ink" and then back to "Automatic" or "Wintab".

My guess at the moment is that the context is enabled before the window has fully initialized, leading to bad behavior which is fixed when it is later disabled/enabled.

https://developer.blender.org/P1936

Triaging note - Wintab was modified to check if the context is enabled before enabling itself. The Wintab implementation may be falsely returning that it is enabled, thus we never enable it.